4. Modul Praktikum Fisika Dasar II

PRINSIP KERJA ALAT UKUR PRAKTIKUM FISIKA DASAR II

TRANSFORMATOR Transformator

digunakan

untuk

mengubah

tegangan.

Penggunaan

di

Laboratorium umumnya untuk menurunkan tegangan listrik PLN 110 atau 220 volt menjadi tegangan AC 6 atau 12 volt, dipakai step down transformator. Untuk menaikkan tegangan sebelum tegangan listrik dikirim ketempat yang pemakaiannya digunakan transformator step up. Maksud dari menaikkan tegangan adalah untuk mengurangi kehilangan energi karena melalui tahanan yang besar. Hal ini dapat dijelaskan sebagai berikut: Kehilangan energi adalah = i . R, dengan menaikkan tegangan V, arus i kehilangan energi akan berkurang.

VOLT-METER DAN AMPERE-METER Yang perlu diperhatikan adalah memperbesar jangkauan ukur. Dengan jangkauan ukur tertentu suatu pengukuran tahanan dapat diperbesar. Misalkan tahanan dalam pengukuran tegangan = r Ohm dan bahwa dengan tahanan muka R akan diperbesar a kali:

L

V

R V

V

V L

Penuntun Praktikum Fisika Dasar II

1

MEMPERBESAR JANGKAUAN UKUR VOLT-METER Buat simpangan yang sama, maka arus i melalui pengukuran sama dengan hukum Ohm:

i 

a V V  R Rr

R  r  a R R  (a  1) r

Misalkan r = 100 Ohm dan jangkauan ukur akan diperbesar a = 1000 kali, maka tahanan muka R yang diperlukan adalah 999 r = 99900 Ohm dengan suatu tahanan sejajar, maka jangkauan ukur suatu pengukur arus dapat diperbesar a kali.

A

A

V

1. R

MEMPERBESAR JANGKAUAN UKUR AMPERE-METER Buat simpangan yang sama, maka arus i melalui pengukuran sama dengan hukum Ohm: i r  (a  1) i R

R 

r a 1

Misalka r = 10 Ohm dan jangkauan amperemeter hendak diperbesar a = 100 kali dengan jajar R, maka R 

1 Ohm. 99 r

Penuntun Praktikum Fisika Dasar II

2

TEORI KETIDAKPASTIAN PENGUKURAN DALAM PERCOBAAN I. PENDAHULUAN Pada percobaan Fisika hasil yang diperoleh biasanya tidak dapat langsung diterima karena harus dipertanggungjawabkan keberhasilan dan kebenarannya. Hal ini disebabkan oleh kemampuan manusia yang terbatas dan ketelitian alat-alat yang digunakan serta mempunyai batas kemampuan tertentu. Dengan kata lain peralatan dan sarana (termasuk waktu) yang tersedia bagi kita membatasi tujuan dan hasil yang dapat dicapai. Hasil percobaan baru dapat diterima apabila harga besaran yang diukur dilengkapi dengan batas-batas penyimpangan dari hasil tersebut, yang disebut sesatan (ketidakpastian). Jika hasil tersebut diketahui penyimpangan terlalu besar maka bila diperlukan percobaan harus diulang kembali dengan berbagai cara misalnya : Mengulang pengukuran beberapa kali yang lebih teliti atau mengganti alat-alat percobaan dengan alat yang lebih baik ketelitiannya. Jadi jelaslah untuk keperluan ini mutlak diperlukan teori sesatan (ketidakpastian). Dengan demikian dapat ditentukan sesatan pada hasil percobaan agar dapat memberi penilaian yang baik.

II. KETIDAKPASTIAN PADA PENGUKURAN Kesalahan atau Error dalam suatu percobaan dapat dibagi atau dua golongan yaitu : II.1. Kesalahan Bersistem (Systematic Error) Kesalahan yang bersumber pada alat pengukuran yang dipakai besarannya, kesalahan biasanya konstant sehingga sering sekali dinamakan sebagai kesalahan konstan (Constant Error). Kesalahan Bersistem ini dapat terjadi karena : a. Kesalahan titik nol (Zero Error). b. Kesalahan pada kalibrasi pengukuran. c. Kesalahan orangnya (pengamat), kesalahan ini disebabkan oleh kebiasaan seorang pengamat. Misalnya seorang pengamat sering kali membuat kesalahan karena kedudukan matanya terlalu rendah atau terlalu tinggi sewaktu membaca tinggi kolam air didalam pipa yang tegak. Kesalahan ini disebut : Parallak. Penuntun Praktikum Fisika Dasar II

3

d. Terjadinya gesekan dan fatiqua (kesalahan) pada alat karena sering dipakai. e. Kondisi percobaan, jika sebuah alat digunakan dengan kondisi percobaan yang berbeda dengan kondisi sewaktu kalibrasi, akan menghasilkan kesalahan. f. Gangguan teknis : misalnya pada waktu pengukuran terjadi gangguan seperti adanya

kebocoran-kebocoran

yang

akan

mengganggu

system

dan

menyebabkan kesalahan.

II.2. Kesalahan Random Karena pengulangan pengukuran selalu memberikan hasil yang berbeda-beda, maka harga tersebut juga akan berbeda dengan harga yang sebenarnya. Kesalahan ini dinamakan kesalahan Random atau kesalahan kebetulan, yang terjadi atas : a. Kesalahan penafsiran, kebanyakan alat pengukuran memerlukan suatu penafsiran pada bagian skala tertentu dan penafsiran ini dapat berubah dari waktu kewaktu yang lain. b. Keadaan penyimpangan, seperti suhu, tekanan udara, atau tegangan listrik. c. Gangguan, misalnya : adanya getaran mekanis atau pengaruh putaran motor dari alat listrik. d. Definisi, walaupun proses pengukuran telah sempurna, pengulangan pengukuran yang sama selalu akan memberikan penyimpangan, besaran yang diamati tidak didefinisikan secara tetap. Misalnya : Panjang suatu meja persegi bukanlah suatu besaran yang terdefinisi secara eksak. Hal ini disebabkan bahwa kalau kita teliti, sisi meja tidaklah rata ataupun mungkin tidak tepat sejajar. Sehingga walaupun kita menggunakan alat ukur yang sangat baik untuk mengukur meja tersebut, harga yang diperolah selalu berubah-ubah tergantung penampang panjang yang kita ukur.

II.3. Kesalahan-Kesalahan Lain Kesalahan lain yang tidak termasuk bahasan 1 dan 2 yang perlu diperhatikan adalah :

Penuntun Praktikum Fisika Dasar II

4

a. Kekeliruan membaca alat atau skala alat dan mengatur kondisi percobaan. Kesalahan ini dapat diatasi dengan cara melakukan percobaan seteliti mungkin atau bila memungkinkan mengulangi percobaan tersebut. b. Kesalahan perhitungan, yaitu kesalahan memasukkan harga atau angka-angka perhitungan,

menggunakan

kalkulator,

menggunakan

daftar

logaritma

dan

sebagainya.

III. PERHITUNGAN KESALAHAN III.1. Sesatan Taksiran Bila pengukuran dilakukan hanya satu kali biasanya sesatan diambil setengah kali skala terkecil dari alat ukur yang digunakan. Contoh : Menggunakan mistar yang skala terkecil 1 mm, bila tebal plat diukur menghasilkan 50 mm, maka hasilnya dapat ditulis : t = ( 50  0,5 ) mm atau = ( 5,0  0,05 ) x 10 mm

t = 0,5 adalah sesatan mutlak (absolut), sedangkan sesatan relatifnya dapat dinyatakan dengan : =

t t

=

0,5 x 100% 50

x 100%

= 1%

III.2. Menentukan Harga Rata-rata (nilai terbaik) dan Sesatannya Misalkan kita melakukan N kali pengukuran didapat hasil sebagai berikut : X1, X2, X3, ……… , XN Untuk mendapatkan nilai yang terbaik (benar) dari pengukuran tersebut adalah merataratakan hasil pengukuran tersebut, yaitu : XN 

X 1  X 2  X 3  ...  X N  N

X

N

N

(III.2.1)

( X N = rata-rata = nilai terbaik), maka simpangan atau deviasi untuk : Penuntun Praktikum Fisika Dasar II

5

X1 adalah X1 = X1 - X X2 adalah X2 = X2 - X XN adalah XN = XN - X  Harga sesatan rata-rata adalah :

X 

X 1  X  X 2  X  X 3  X  ...  X N  X N



 X  X 

XN  X

(III.2.2)

N

Persamaan (III.2.2) ini disebut deviasi rata-rata. Sedangkan deviasi standar atau simpangan baku semesta X(x) : didefinisikan sebagai :

x 

Vx

Dimana Vx adalah variasi yang didefinisikan

(X

Vx 

2

N

 XN)

N

dengan N menuju tak hingga. Sehingga x dapat dituliskan : 2

x 

Vx 

(X N  X N ) N

(III.2.3)

dengan N menuju tak hingga. Harga x berada pada pengukuran tak terhingga yang tidak mungkin dilakukan dengan menggunakan suatu pendekatan teori samping x dapat diganti dengan SN

yang

dinamakan simpangan baku contoh (sample standard deviation).  N memberikan gambaran tentang simpangan X terhadap Xo. Sedangkan SN menggambarkan simpangan X terhadap X N maka : 2

(X N  X ) ( N  1)

SN  yang dapat diubah menjadi,

2

SN 

( X N2  N X ) ( N  1)

(III.2.4)

Dimana N  8 (untuk N = 1  SN tidak mempunyai arti). Penuntun Praktikum Fisika Dasar II

6

Menurut teori percobaan SN sebenarnya adalah S X N yaitu ketidakpastian pada nilai ratarata contoh XN yang mempunyai harga

SXN 

SN

(III.2.5)

N

Penggantian SN menjadi SX hal ini disebabkan kurva sebaran nilai rata-rata contoh X lebih sempit dari pada kurva sebaran pengukuran tunggal (X1) berarti  x 

X yaitu

kita mengulangi pengukuran N kali dengan hasil rata-rata, misalnya X 1 maka ada kepastian 66% X 1 terletak dalam selang X N   X

didalam praktek percobaan tak

terhingga, tak mungkin kita lakukan, jadi  X dan  X tidak dapat diketahui dan sebagai pengganti terbaik dipakai SN dan S X N seperti diatas. Untuk pemakaian selanjutnya digunakan,

X  S X N 

SN N



X

2 N

2

 NX N

N ( N  1)

(III.2.6)

dengan N  8. Apabila X diukur N kali, ada kemungkinan 68% bahwa simpangan nilai rata-rata contoh X terhadap nilai benar Xo tidak lebih dari S X N dengan kata lain “ada jaminan 68%

bahwa Xo ada dalam interval X  S X N ” dengan demikian persoalan selesai. Kita tidak dapat mengetahui nilai benar Xo dari eksperimen, tetapi dengan mengadakan pengulangan cukup banyak, kita dapat menyodorkan sebagai penggantinya nilai contoh X dan dapat memberikan pernyataan sampai berapa jauh X menyimpang dari Xo.

Contoh : X = 10,0; 10,2; 10,0; 10,0; 9,8; 10,1; 9,8; 10,3; 9,8; 10,0 Maka nilai terbaik X dan sesatannya ( X  X) dapat dicari sebagai berikut : N

XN

1 2 3 4 5 6 7 8

10,0 10,2 10,0 10,0 9,8 10,1 9,8 10,3

Penuntun Praktikum Fisika Dasar II

X N2 100,00 104,04 100,00 100,00 96,04 102,01 96,04 106,09

7

9 10

XN 

9,8 10,0  XN = 100,0

X

N

N



96,04 100,00  X N2 = 1000,26

100,0  10,0 10

( X N ) 2  (10,0) 2  100,0

X  S X N  



X

2 N

2

 NX N

N ( N  1)

1000,26

 10 x100,0

10(10  1)

0,26  0,05 90

maka nilai terbaik X = ( 10,00  0,05 )

III.3. Contoh Perhitungan III.3.1. Ketelitian Pengukuran Suatu amperemater mempunyai skala 0 – 5 A, dengan pembagian skala terkecil 0,1 A. (a). Berapa ketelitian alat itu bila skala pada pengukuran, skala penuh ? (b). Dan pada setengah skala ? Jawab : (a). I = ½ skala terkecil = ½ x 0,1 A, dan I = 5 A Ketelitian

I 0,05  x 100%  1% I 5

(b). I = ½ skala terkecil = ½ x 0,1 A = 0,05 A, dan I = 2,5 A Ketelitian

I 0,05  x 100%  2% I 2,5

III.3.2. Sesatan Yang Ditentukan Oleh Skala Alat 1. Tahanan sepotong kawat ditentukan menurut hokum ohm. Hasilnya adalah V = ( 1,0  0,05 ) volt dan I = ( 5,0  0,05 ) mA atau I = ( 5,0  0,05 ) x 10-3 A. Penuntun Praktikum Fisika Dasar II

8

Berapakah  R ? Jawab : R 

V 1,0   200 ohm I 5,0 x 10 3

R V  R V

I I



R 0,05   200 1,0

0,05 5

R  ( 0,05  0,01) x 200  12 ohm

Jadi R = ( 200  12 ) ohm

2. Pada percobaan tegangan permukaan air digunakan rumus : h 

2 gr

Bila : r = ( 0,30  0,005 ) mm g = ( 980  2% ) cm/det2  = 1,0 g/cm3 dan h = ( 50,0  0,05 ) mm Tentukan :  dan  Jawab : h 

2 gr



 

h gr 50,0 x 1,0 x 980 x 0,30  2 2

  73,50 





h  h

g  g

 0,05   73,50 50

r r

0,02  980

(tidak mempunyai sesatan)

0,005 0,30

 0,0018

  0,0018 x 73,50  0,13

Jadi   ( 73,50  0,13 ) dyne.

3. Sesatan yang paling mempengaruhi Rumus lensa tipis (Gauss) : f 

S S' S  S'

Bila S = ( 8,0  0,05 ) cm dan S’ = ( 24,0  0,05 ) cm Penuntun Praktikum Fisika Dasar II

9

Berapakah ( f  f ) ? Jawab: S S' S  S'

f 



1 1 1   f S S'

1 1 1   f 8,0 24,0 f  6,0 cm

f f



f (6,0) 2

S  S



0,05 (8,0) 2

S ' S'



0,05 (24,0) 2

 0,008678

f  0,008678 x (6,0) 2  0,0312

Jadi f  ( 6,00  0,03 ) cm.

Penuntun Praktikum Fisika Dasar II

10

I. ELEKTROLISA

1.1. TUJUAN PERCOBAAN Menentukan tara kimia listrik dan muatan elementer dengan cara elektrolisa.

1.2. ALAT DAN BAHAN 1. Sel elektrolisa larutan CuSO4. ...................................................................................................................................... 2. Elektroda tembaga (Cu). ...................................................................................................................................... 3. Catu daya. ...................................................................................................................................... 4. Amperemeter. ...................................................................................................................................... 5. Pengering elektroda tembaga (Cu). ...................................................................................................................................... 6. Amplas. ...................................................................................................................................... 7. Neraca Analitis. ......................................................................................................................................

Penuntun Praktikum Fisika Dasar II

11

1.3. DASAR TEORI A. Menentukan Tara Kimia Listrik Bila arus listrik (DC) dialirkan melalui sel elektrolit yang berisi larutan garam AB, maka garam tersebut akan terurai sebagai berikut: AB

——→

A+ + B-

Ion yang bermuatan positif akan menempel pada elektroda negatif (katoda). Dengan menimbang katoda sebelum dan sesuadah dialiri arus listrik, maka dapat diketahui jumlah logam yang menempel pada elektroda tersebut, yaitu: W = z.i.t

...................................................... (1)

dimana: W = jumlah massa yang diendapkan (kg) z = tara kimia listrik [kg/(amp)(jam)] i = kuat arus (ampere) t = waktu pengaliran arus (jam)

B. Menghitung Besar Muatan Elementer Percobaan elektrolisa tersebut dapat digunakan untuk menghitung muatan elementer dari percobaan Millikan. Setiap ion tembaga menerima dua muatan elektron dari katoda yang mengakibatkan ion itu menjadi atom netral dan menempel pada elektroda tersebut. Apabila terdapat N atom Cu yang dipindahkan, jumlah muatan listrik yang pindah adalah 2eN. Maka muatan elementer dapat dihitung:

e 

Ait 2W N o

....................................................... (2)

dimana: e = muatan elementer (Coulomb) A = berat atom Cu (63,5 gram/mole) W = Jumlah massa yang diendapkan (gram) No = Bilangan Avogadro (6,02 x 1023 atom/mole)

Penuntun Praktikum Fisika Dasar II

12

Gambar 1. Skema rangkaian elektrolisa

1.4. PROSEDUR PERCOBAAN 1. Bersihkan plat katoda dan timbang dengan neraca. 2. Pasang katoda ekstra seperti pada Gambar 1. dan tentukan besar arus (sekitar 2A) dengan mengatur besar hambatan geser. 3. Ganti katoda ekstra dengan katoda yang sudah ditimbang. 4. Setelah elektrolisa selesai, katoda dicelupkan ke dalam air, supaya larutan CuSO4 yang menempel hilang (jangan digosok supaya Cu yang menempel pada katoda tidak berkurang). Kemudian keringkan dengan alat pengering (hair dryer). 5. Timbang katoda tersebut dan catat jumlah massa yang diendapkan. 6. Lakukan percobaan berturut-turut selama 5, 10, dan 20 menit. Perhatian: - Jaga arus listrik agar tetap konstan. - Menimbang katoda harus dalam keadaan kering.

Penuntun Praktikum Fisika Dasar II

13

1.5. TUGAS PENDAHULUAN 1. Bagaimana pernyataan hukum Faraday untuk elektrolisa. 2. Apa hubungan tara kimia listrik dengan muatan elementer. 3. Mengapa dua sel elektrolit pada percobaan ini di hubungkan secara seri? 4. Tulis definisi tara kimia listrik. 5. Samakah harga tara kimia listrik perak (Ag) dengan tembaga (Cu). Larutan apakah yang dapat digunakan untuk mengukur tara kimia listrik perak. 6. Buktikan rumus (2). 7. Jelaskan maksud dari tegangan elektrolisa pada sel elektrolit. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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15

1.6. DATA HASIL PENGAMATAN

No.

t (menit)

1.

5

2.

10

3.

20

i (A)

Go (gram)

G1 (gram)

Catatan: Go = massa awal katoda G1 = massa akhir katoda W = G1 - Go

Penuntun Praktikum Fisika Dasar II

16

1.7. PENGOLAHAN DATA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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19

1.8. ANALISA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

20

1.9. TUGAS AKHIR 1. Hitung besar tara kimia listrik (z) pada percobaan anda dengan menggunakan persamaan (1). 2. Hitung besar muatan elementer (e) dengan menggunakan persamaan (2), bandingkan hasil yang didapatkan dengan literatur (e = 1,602 x 10-19 C) . ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

21

1.10. KESIMPULAN ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

22

LAMPIRAN GAMBAR

Penuntun Praktikum Fisika Dasar II

23

II. HUKUM OHM

2.1. TUJUAN PERCOBAAN 1. Memahami pengertian tentang hukum Ohm. 2. Mempelajari dan memahami sistem rangkaian tunggal, seri dan paralel.

2.2. ALAT DAN BAHAN 1. Amperemeter DC. ...................................................................................................................................... 2. Voltmeter DC/ Multimeter. ...................................................................................................................................... 3. Catu daya arus searah. ...................................................................................................................................... 4. Resistor ......................................................................................................................................

Penuntun Praktikum Fisika Dasar II

24

2.3. DASAR TEORI Seorang ahli fisika bangsa Jerman yaitu George Ohm menyatakan bahwa antara arus, ggl (tegangan) dan resistansi ada hubungan sebagai berikut: E  I R

..................................................... (1)

dimana: E = ggl (volt) I = Arus yang mengalir pada rangkaian (Ampere) R = Resistansi (Ohm)

Dalam suatu rangkaian, ada yang membutuhkan tegangan pada beban selalu tetap dan atau agar arus yang sampai juga tetap, untuk maksud tersebut harus diatur suatu sistem rangkaian seri dan paralel.

Penuntun Praktikum Fisika Dasar II

25

2.4. PROSEDUR PERCOBAAN A. Rangkaian Tunggal 1. Susun rangkaian percobaan seperti Gambar 1 dibawah ini. 2. Dengan menatur Rg, maka kita dapatkan harga arus yang sesuai, dengan terlebih dahulu menentukan harga Rs. 3. Catat besar tegangan (V) dan arus (A) pada rangkaian. 4. Ulangai untuk harga E yang berbeda. 5. Kemudian untuk E yang tetap, catat tegangan (V) dan arus (A) pada rangkaian, untuk harga Rs yang berbeda.

Gambar 1. Rangkaian Tunggal

B. Untuk Rangkaian Seri 1. Susun rangkaian percobaan seperti Gambar 2, seperti berikut:

Gambar 2. Rangkaian Seri Penuntun Praktikum Fisika Dasar II

26

2. Dengan harga R1, R2 dan R3 tertentu, atur arus yang mengalir dengan pengaturan Rg (tahanan geser). 3. Ukur tegangan pada masing-masing tahanan. 4. Ulangi untuk harga arus yang berbeda.

C. Untuk Rangkaian Paralel 1. Susun rangkaian percobaan seperti Gambar 3, seperti berikut:

Gambar 3. Rangkaian Paralel

2. Dengan harga R1, R2 dan R3 tertentu, atur arus yang mengalir dengan pengaturan Rg (tahanan geser). 3. Ukur tegangan pada masing-masing tahanan. 4. Ulangi untuk harga arus yang berbeda.

Penuntun Praktikum Fisika Dasar II

27

2.5. TUGAS PENDAHULUAN 1. Jelaskan pengertian Hukum Ohm menurut Anda jika ditinjau dari persamaan : V = I.R 2. Beda potensial 15 V harus diberikan pada ujung-ujung seutas kawat agar arus 2,5 A mengalir melalui kawat tersebut. Berapa hambatan listrik kawat? 3. Ceritakan awal mula ditemukannya Hukum Ohm? ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

28

2.6. DATA HASIL PENGAMATAN A. Rangkaian Tunggal: No.

E (volt)

R ()

1

10

25

2

10

50

3

10

100

I (A)

V (Volt)

B. Rangkaian Seri: No.

E (volt)

1

R (Ohm)

V (Volt)

R1

R2

R3

10

25

50

100

2

10

25

50

100

3

10

25

50

100

V1

V2

V3

I (A)

C. Rangkaian Paralel: No.

E (volt)

1

R (Ohm)

I (A)

R1

R2

R3

10

25

50

100

2

10

25

50

100

3

10

25

50

100

Penuntun Praktikum Fisika Dasar II

I1

I2

I3

V (Volt)

29

2.7. PENGOLAHAN DATA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

30

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

31

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

32

2.8. ANALISA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

33

2.9. TUGAS AKHIR 1. Apa kelebihan dan kekurangan dari rangkaian yang disusun secara seri? 2. Apa kelebihan dan kekurangan dari rangkaian yang disusun secara paralel? 3. Sebutkan contoh penggunaan Hukum Ohm dalam kehidupan sehari-hari? 4. Apa perbedaan percobaan Hukum Ohm dengan Hukum Kirchoff? ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

34

2.10. KESIMPULAN ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

35

LAMPIRAN GAMBAR

Penuntun Praktikum Fisika Dasar II

36

III. JEMBATAN WHEATSTONE

3.1. TUJUAN PERCOBAAN 1. Mengukur besar hambatan, kapasitas dan membuktikan hukum hubungan seri dan parallel. 2. Menentukan hambatan jenis suatu kawat penghantar.

3.2 ALAT DAN BAHAN 1.

Kawat geser (L). ......................................................................................................................................

2. Hambatan, kapasitor dan kawat penghantar. ...................................................................................................................................... 3. Galvanometer (G). ...................................................................................................................................... 4. Catu daya arus searah. ...................................................................................................................................... 5. Generator nada. ......................................................................................................................................

Penuntun Praktikum Fisika Dasar II

37

3.3. DASAR TEORI Jembatan Wheatstone adalah rangkaian yang terdiri atas empat buah hambatan seperti terlihat pada Gambar 1. berikut:

Gambar 1. Skema Jembatan Wheatstone

R1, R2 dan R3 merupakan hambatan-hambatan yang sudah diketahui harganya, sedangkan Rx besar hambatan yang akan dicari. Pada keadaan galvanometer (G) menunjukkan angka nol, berlaku hubungan:

Rx 

R1 R3 R2

..................................................... (1)

Jika Rx diganti dengan Cx dan R3 diganti dengan C3, maka diperoleh hubungan:

Cx 

R1 C3 R2

..................................................... (2)

Dalam percobaan, harga R1 dan R2 sebanding dengan l1 dan l2 (lihat Gambar 2), sedangkan R3 dan C3 diganti dengan hambatan standard RS dan kapasitor standard CS, sehingga persamaan (1) menjadi: Rx 

l1 Rs l2

..................................................... (3)

l1 Cs l2

..................................................... (4)

Sedangkan persamaan (2) menjadi:

Cx 

Untuk menentukan hambatan jenis suatu kawat penghantar, digunakan persamaan: R  

L A

..................................................... (5)

dengan : Penuntun Praktikum Fisika Dasar II

38

R = hambatan kawat L = Panjang kawat A = Luas penampang kawat

 = Hambatan jenis kawat

Gambar 2. Rangkaian Jembatan Wheatstone

Penuntun Praktikum Fisika Dasar II

39

3.4. PROSEDUR PERCOBAAN A. Mengukur Besar Hambatan. 1. Susunlah rangkaian percobaan seperti Gambar 2. 2. Atur kontak geser K sehingga galvanometer menunjukkan angka nol. 3. Catat panjang l1 dan l2. 4. Ganti Rx dengan Ry dan lakukan langkah 2. dan 3. Ulangi untuk Rx dan Ry yang dihubungkan secara seri dan paralel. 5. Lakukan masing-masing minimal 3 kali.

B. Menentukan Hambatan Jenis Kawat Penghantar. 1. Dari Gambar 2, ganti Rx dengan kawat penghantar. 2. Catat panjang dan diameter kawat penghantar. 3. Lakukan seperti prosedur kerja A.2. dan A.3. untuk panjang kawat yang berbedabeda. (Sekurang-kurangnya 3 panjang kawat).

Penuntun Praktikum Fisika Dasar II

40

3.5. TUGAS PENDAHULUAN 1. Jelaskan cara lain untuk mengukur hambatan. 2. Buktikan persamaan (1), (2), (3) dan (4). 3. a. Apakah syarat agar R1 dan R2 sebanding dengan I1 dan I2. b. Bagaimana pengaruh pengukuran jika kawat geser tidak homogen. 4. Apakah satuan hambatan jenis (satuan SI). ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... ......................................................................................................................................... Penuntun Praktikum Fisika Dasar II

41

3.6. DATA HASIL PENGAMATAN A. Mengukur Besar Hambatan (RX) No.

l1 (cm)

E

RS

(volt)

(Ohm)

1

2

3

l2 (cm) 4

5

1

2

3

4

5

1. 2. 3.

B. Menentukan Hambatan Jenis Kawat Penghantar ()

No.

E (volt)

Panjang Kawat,

Diameter Kawat,

L (cm)

D (cm)

R (Ohm) 1

2

3

1

2

3

1. 2. 3.

Penuntun Praktikum Fisika Dasar II

42

3.7. PENGOLAHAN DATA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

43

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

44

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

45

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

46

3.8. ANALISA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

47

3.9. TUGAS AKHIR 1. a. Hitung besar Rx, Ry dan hambatan pengganti Rx dan Ry yang dihubungkan secara seri dan paralel. b. Berdasarkan hasil percobaan, tentukan hukum hubungan seri dan paralel pada hambatan. 2. a. Hitung hambatan jenis kawat penghantar dari grafik antara R terhadap panjang kawat. b. Dengan melihat literatur, tentukan jenis bahan kawat penghantar tersebut. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

48

3.10. KESIMPULAN ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

49

LAMPIRAN GAMBAR

Penuntun Praktikum Fisika Dasar II

50

IV. HUKUM KIRCHHOFF

4.1. TUJUAN PERCOBAAN 1. Mempelajari hukum tegangan Kirchhoff dan hukum arus Kirchhoff. 2. Mempelajari rangkaian loop banyak (multiloop circuit).

4.2. ALAT DAN BAHAN 1.

Papan rangkaian terdiri atas Hambatan...................................................................................................................... Catu daya......................................................................................................................

2. Alat ukur arus dan tegangan listrik ......................................................................................................................................

Penuntun Praktikum Fisika Dasar II

51

4.3. DASAR TEORI Arus yang mengalir pada setiap bagian rangkaian yang rumit dapat diselesaikan dengan menggunakan hukum Kirchhoff yaitu: 1. Pada rangkaian tertutup jumlah sumber tegangan akan sama dengan jumlah penurunan potensial. 2. Jumlah arus yang masuk suatu sambungan akan sama dengan jumlah arus yang melewati dari sambungan tersebut.

Gambar 1. Rangkaian Multiloop

Penggunaan hukum Kirchhoff pada Gambar 1, menghasilkan:

I1  I 2  I 3

E1  I1 R1  I 2 R2 E2  I 2 R2  I 3 R3

......................................... (1)

Dari ketiga persamaan tersebut dapat diperoleh: I1 

R2 ( E1  E 2 )  R3 E1 R1 R2  R2 R3  R3 R1

............................. (2)

I2 

Penuntun Praktikum Fisika Dasar II

R1 E 2  R3 E1 R1 R2  R2 R3  R3 R1

52

4.4. PROSEDUR PERCOBAAN 1. Mempelajari Hukum Tegangan Kirchhoff. A.1. Hukum Kirchhoff Pada Rangkaian Seri: 1. Susunlah rangkaian percobaan seperti Gambar 2. 2. Ukurlah tegangan sumber (E). 3. Ukur tegangan pada ujung-ujung R1, R2 dan R3. 4. Ulangi percobaan ini untuk harga R yang lain.

Gambar 2. Rangkaian Hambatan Seri dan Baterai

A.2. Hukum Kirchhoff Pada Rangkaian Paralel: 1. Susunlah rangkaian percobaan seperti Gambar 3. 2. Ukurlah tegangan sumber (E). 3. Ukur tegangan pada ujung-ujung R1, R2, R3 dan R4. 4. Ulangi percobaan ini untuk harga R yang lain.

Gambar 3. Rangkaian Hambatan Seri dan Paralel

2. Mempelajari Hukum Arus Kirchhoff. 1. Susunlah rangkaian percobaan seperti Gambar 4. 2. Tentukan besar tegangan E yang digunakan. 3. Ukur arus yang melewati hambatan R1, R2, R3, R4, dan R5. 4. Ulangi langkah 3, jika polaritas sumber tegangan dibalik.

Penuntun Praktikum Fisika Dasar II

53

Gambar 4. Rangkaian Hambatan Seri dan Paralel

4.5. TUGAS PENDAHULUAN 1.

Buktikan persamaan (2).

2.

Gunakan hukum tegangan Kirchhoff untuk menjelaskan rangkaian pada Gambar 2 dan 3.

3.

Gunakan hukum arus Kirchhoff untuk menjelaskan rangkaian pada Gambar 4.

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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4.6. DATA HASIL PENGAMATAN A. Mempelajari Hukum Tegangan Kirchhoff. A.1. Hukum Kirchhoff Pada Rangkaian Seri: R (Ohm)

E

No.

V (Volt)

(Volt)

R1

R2

R3

1.

10

25

50

100

2.

10

25

50

100

3.

10

25

50

100

V1

V2

V3

A.2. Hukum Kirchhoff Pada Rangkaian Paralel: R (Ohm)

E

No.

V (Volt)

(Volt)

R1

R2

R3

R4

1.

10

25

100

25

100

2.

10

25

100

25

100

3.

10

25

100

25

100

V1

V2

V3

V4

B. Mempelajari Hukum Arus Kirchhoff. No.

R (Ohm)

E

I (Ampere)

(Volt)

R1

R2

R3

R4

R5

1.

10

25

50

50

50

25

2.

10

25

50

50

50

25

3.

10

25

50

50

50

25

Penuntun Praktikum Fisika Dasar II

I1

I2

I3

I4

I5

56

4.7. PENGOLAHAN DATA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

57

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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4.8. ANALISA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

61

4.9. TUGAS AKHIR 1. Buktikan bahwa hukum tegangan Kirchhoff berlaku untuk rangkaian seri dan paralel. 2. Buktikan bahwa hukum arus Kirchhoff berlaku untuk arus dipersambungan. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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4.10. KESIMPULAN ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

63

LAMPIRAN GAMBAR

Penuntun Praktikum Fisika Dasar II

64

V. INDUKSI MAGNET 5.1. TUJUAN PERCOBAAN 1. Memahami prinsip kuat medan magnet (induksi magnet). 2. Menentukan induksi magnet (B) pada solenoida (lilitan kawat) yang dialiri arus, tanpa dan dengan pengaruh medan magnet luar.

5.2. ALAT DAN BAHAN 1.

Catu daya ......................................................................................................................................

2. Amperemeter ...................................................................................................................................... 3. Solenoida ...................................................................................................................................... 4. Magnet Batang ...................................................................................................................................... 5. Batang logam (Paku) ......................................................................................................................................

Penuntun Praktikum Fisika Dasar II

65

5.3. DASAR TEORI Jika sebuah kumparan kawat (selenoida) dialiri arus, I maka akan terjadi induksi magnet seperti Gambar (1), B L

I

N

Gambar 1. Induksi magnet

kuat medan magnet (induksi magnet, B) dengan satauan Tesla (T) yang terjadi dapat dihitung dengan persamaan (1), berikut: N B  o I   L

dimana:

..................................................... (1)

o = momen magnet = 4 x 10-7 T.m / A I = Arus yang mengalir pada lilitan (Ampere) N = Banyaknya lilitan L = Panjang lilitan (m)

Sedangkan besar fluks magnet (B) dengan sataun Weber (Wb = T.m2) pada kumparan kawat tersebut dapat dihitung dengan persamaan (2), berikut:

B  B A dimana :

.................................................................. (2)

B = kuat medan magnet (induksi magnet), (Tesla, T). A = Luas Penampang kumparan (m2)

Penuntun Praktikum Fisika Dasar II

66

5.4. PROSEDUR PERCOBAAN 1. Susun peralatan percobaan seperti Gambar 2, berikut:

L

I

E

N

Gambar 2. Rangkaian percobaan

2. Tentukan jumlah dan panjang lilitan kawat yang digunakan. 3. Tentukan besar arus yang mengalir pada lilitan kawat dengan dan tanpa medan magnet luar. 4. Ulangi langkah 1 sampai 3 dengan masing-masing minimal 5 kali pengukuran.

Penuntun Praktikum Fisika Dasar II

67

5.5. TUGAS PENDAHULUAN 1.

Apa yang disebut dengan kuat medan magnet (induksi magnet).

2.

Apa yang disebut dengan momen magnet () dan harganya dipengaruhi oleh apa.

3.

Buktikan persamaan (1) dan (2).

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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5.6. DATA HASIL PENGAMATAN 1. Tanpa Bahan didalam lilitan.

No.

E

Diameter

(volt)

lilitan, D(cm)

Jumlah lilitan,

Panjang lilitan,

N (lilitan)

L (cm)

1.

4

50

2.

4

50

3.

4

50

4.

4

50

5.

4

50

No.

E

Diameter

(volt)

lilitan, D(cm)

Jumlah lilitan,

Panjang lilitan,

N (lilitan)

L (cm)

1.

4

100

2.

4

100

3.

4

100

4.

4

100

5.

4

100

I (Ampere)

I (Ampere)

2. Dengan Magnet Batang didalam lilitan.

No.

E

Diameter

(volt)

lilitan, D(cm)

Jumlah lilitan,

Panjang lilitan,

N (lilitan)

L (cm)

1.

4

50

2.

4

50

3.

4

50

4.

4

50

5.

4

50

Penuntun Praktikum Fisika Dasar II

I (Ampere)

69

No.

E

Diameter

(volt)

lilitan, D(cm)

Jumlah lilitan,

Panjang lilitan,

N (lilitan)

L (cm)

1.

4

100

2.

4

100

3.

4

100

4.

4

100

5.

4

100

I (Ampere)

3. Dengan batang logam didalam lilitan.

No.

E

Diameter

(volt)

lilitan, D(cm)

Jumlah lilitan,

Panjang lilitan,

N (lilitan)

L (cm)

1.

4

50

2.

4

50

3.

4

50

4.

4

50

5.

4

50

No.

E

Diameter

(volt)

lilitan, D(cm)

Jumlah lilitan,

Panjang lilitan,

N (lilitan)

L (cm)

1.

4

100

2.

4

100

3.

4

100

4.

4

100

5.

4

100

Penuntun Praktikum Fisika Dasar II

I (Ampere)

I (Ampere)

70

5.7. PENGOLAHAN DATA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

71

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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5.8. ANALISA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

75

5.9. TUGAS AKHIR 1.

Tentukan kuat medan magnet (induksi magnet) B dari masing-masing percobaan..

2.

Tentukan besar fluks magnetnya (B).

3.

Jelaskan hubungan antara kuat medan magnet (induksi magnet) (B) dengan fluks magnet (B).

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

77

5.10. KESIMPULAN ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

78

LAMPIRAN GAMBAR

Penuntun Praktikum Fisika Dasar II

79

VI. TRANSFORMATOR

6.1. TUJUAN PERCOBAAN 3. Mempelajari perbandingan tegangan dengan banyaknya lilitan. 4. Mempelajari perbandingan arus dengan banyaknya lilitan. 5. Mempelajari

Transformator

dengan

beban

(karakteristik

tegangan-arus,

karakteristik daya arus). 6. Menghitung kerugian dan efisiensi transformator.

6.2. ALAT DAN BAHAN 5. Papan panel soket ...................................................................................................................................... 6. Potensiometer ...................................................................................................................................... 7. Kumparan 500 lilitan dan 1000 lilitan ...................................................................................................................................... 8. Kabel penghubung ...................................................................................................................................... 9. Catu daya ...................................................................................................................................... 10. Multimeter ...................................................................................................................................... 11. Besi transformer ......................................................................................................................................

Penuntun Praktikum Fisika Dasar II

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6.3. DASAR TEORI Transformer adalah sebuah alat yang terdiri dari lilitan primer, lilitan sekunder dan inti yang berfungsi untuk merubah besaran listrik. Hubungan antara tegangan V, arus I dan lilitan N adalah:

I VP NP   S VS NS IP

......................................... (1)

Kerugian daya pada transformer terjadi pada inti material dan lilitan kawat primer dan sekunder. Kerugian lilitan (kerugian tembaga), dapat dihitung dari tahanan lilitan R dan arus dengan persamaan (2): Kerugian tembaga = I P2 RP  I S2 RS

......................................... (2)

Kerugian inti dapat dihitung dari rangkaian tanpa beban, dengan persamaan (3): Kerugian inti = daya primer - I P2 RP

......................................... (3)

Untuk menghitung efisiensi transformer dapat dilakukan dengan persamaan (4): Efisiensi =

daya keluaran ............... (4) daya keluaran  kerugian tembaga  kerugian inti

Penuntun Praktikum Fisika Dasar II

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6.4. PROSEDUR PERCOBAAN A. Perbandingan Tegangan (Step Up dan Step Down) 1. Susunlah rangkaian percobaan seperti Gambar 1. 2. Ukurlah tegangan primer dan sekunder untuk beberapa harga tegangan. 3. Tukarlah kumparan primer dan sekunder, kemudian lakukan pengukuran seperti langkah 2.

Gambar 1. Skema percobaan perbandingan Tegangan

B. Perbandingan Arus (Step Up dan Step Down) 1. Susunlah rangkaian percobaan seperti Gambar 2. 2. Ukurlah arus primer dan sekunder untuk beberapa harga arus. 3. Tukarlah kumparan primer dan sekunder, kemudian lakukan pengukuran seperti langkah 2.

Gambar 2. Skema percobaan perbandingan Arus

Penuntun Praktikum Fisika Dasar II

82

6.5. TUGAS PENDAHULUAN 1. Mengapa transformer dapat merubah tegangan dan arus. 2. Apa yang disebut dengan transformer step-up dan transformer step-down. 3. Mengapa terjadi kerugian inti dan bagaimana cara mereduksinya. 4. Apa yang anda ketahui tentang isolating, auto transformer dan variable auto transformer. 5. Sebutkan yang dapat memanfaatkan transformer. ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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6.6. DATA HASIL PENGAMATAN A. Perbandingan Tegangan (Step Up dan Step Down)  Step Up No.

Np Ns (lilitan) (lilitan)

Vp (volt) 1 2 3

1.

300

600

12

18

30

2.

300

600

12

18

30

3.

300

600

12

18

30

Vs (volt) 1 2 3

 Step Down No.

Np Ns (lilitan) (lilitan)

Vp (volt) 1 2 3

1.

600

300

12

18

30

2.

600

300

12

18

30

3.

600

300

12

18

30

Vs (volt) 1 2 3

B. Perbandingan Arus (Step Up dan Step Down)  Step Up No.

Np Ns (lilitan) (lilitan)

1.

300

600

2.

300

600

3.

300

600

1

Ip (Ampere) 2 3

1

Is (Ampere) 2 3

 Step Down No.

Np Ns (lilitan) (lilitan)

1.

600

300

2.

600

300

3.

600

300

Ip (Ampere) 1 2 3

Penuntun Praktikum Fisika Dasar II

Is (Ampere) 1 2 3

84

6.7. PENGOLAHAN DATA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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6.8. ANALISA ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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6.9. TUGAS AKHIR 1.

Tentukan hubungan tegangan dengan kumparan transformer.

2.

Tentukan hubungan arus dengan kumparan transformer.

3.

Gambarkan karakteristik tegangan-arus transformer.

4.

Gambarkan karakteristik daya-arus transformer.

5.

Hitung efisiensi transformer.

............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ...............................................................................................................................................

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6.10. KESIMPULAN ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... ............................................................................................................................................... Penuntun Praktikum Fisika Dasar II

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LAMPIRAN GAMBAR

Penuntun Praktikum Fisika Dasar II

92