Physics Investigatory Project Abhishek class xii

Name – Abhishek kumar Class – XII A Roll no.  – 

2015 - 2016

CONTENT CERTI"ICATE

1

AC#NO$%E&'E(ENT

2

AI( O" RO)ECT

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INTRO&+CTION

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 TEOR  TEOR

6-11

O/ERATION

12

CONC%+ION A%ICATION O" E(I

1*

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a!e no.

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RECA+TION /I/%IO'RA

1, 15 16

 This is o 3eri4 3eri4 ha Abhishek kumar o4 3lass XII-A has su33ess4ull 3omlee7 he in8esi!aor ro9e3 ro9e3 on he oi3 :ELECTROMAGNETIC INDUCTION; INDUCTION; un7er m !ui7an3e 7urin! he ear 2015-2016 in he arial 4uls  Tea3her>s si!naure rin3ial ?s si!naure

I @oul7 like o sin3erel an7 ro4usel hank m hsi3s ea3her Mr. Kuldeep  Kuldeep  4or his able !ui7an3e an7 suor in 3omlein! m ro9e3. I @oul7 also like o e=en7 m !raiu7e o he rin3ial 4or ro8i7in! me @ih all he 4a3ili ha @as reBuire7. %as bu no he leas I @oul7 e=en7 m !raiu7e o@ar7s all ea3hin! an7 non ea3hin! sa o4 Tulis inernaional s3hool an7 o@ar7s m 4rien7s @ho has suore7 me o 3omlee his ro9e3. Abhishek kumar

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Electro Magnet:

An ele electr ctroma omagne gnett is a type type of magnet magnet in which which the magnet magnetic ic field field is produc produced ed by electric current. The magnetic field disappears when the current is turned off.

Induction: This process of generating current in a conductor by placing the conductor in a changing magnetic field is called induction.

Electromagnetic Electromagnetic Induction: Electrom Electromagnet agnetic ic induction induction is the production production of a potential potential differen difference ce (voltage) (voltage) across a conductor when it is exposed to a varying magnetic field. Electromagnetic induction is when an electromagnetic field causes molecules in another object to flow. Induction can produce electricity (in coils) heat (in ferrous metals) or waves (in a radio transmitter). !inally it is refers to the phenomenon where an emf is induced when the magnetic flux lin"ing a conductor changes.

Magnetic Flux is defined as the product of the magnetic flux density and the area normal  to  to the field through which the field is passing. It is a scalar #uantity and its $.I. unit is the weber (%b).

φ = B A

Principle: Electr Electroma omagne gnetic tic induct induction ion (or (or someti sometimes mes just just induct induction ion)) is a proces processs where where a conductor placed in a changing magnetic field (or a conductor moving through a stationary magnetic field) causes the production of a voltage across the conductor. This process of electromagnetic induction in turn causes an electrical current & it is said to induce the current.

Invention: 'ichae 'ichaell !arada !aradayy is genera generally lly credi credited ted with with the discov discovery ery of induct induction ion in * * though it may have been anticipated by the wor" of !rancesco +antedeschi +antedeschi in ,-. Around Around * to *, /oseph /oseph 0enry 0enry made made a similar similar discovery discovery but did not publish publish his findings until later

Induced e.m.f.s  1  1

If magnetic flux through a coil is altered then an e.m.f. will be generated in the coil. This effect was first observed and explained expl ained by Ampere and !araday between ,2 and *. !araday discovered that an e.m.f. could be generated either by (a) movin ovingg the the coil or the the sour sourcce of flux flux relat elativ ivee to eac each othe ther or by (b) (b) chan changi ging ng the the magn magnit itud udee of the the sour source ce of magn magneetic tic flux flux in some some way. way. 3ote that the e.m.f. is only produced while the flux is changing. !or example consider two coils as shown in !igure .

4oil A is connected to a galvanometer and coil 5 is connected to a battery and has direct current flowing through it. 4oil A is within the magnetic field produced by 5 and an e.m.f. can be produced in A by moving the coils relative to each other or by changing the si6e of the current in 5. This can be done by using the rheostat 7 switching the current on or off or (c) using an a.c. supply for 5. (An e.m.f. could also be produced in coil A by replacing coil 5 with a permanent magnet and moving this relative to coil A.)

Representation:

Electrom Electromagnet agnetic ic induction induction is the production production of a potential potential differen difference ce (voltage) (voltage) across a conductor when it is exposed to a varying magnetic field.

Working and onstruction: 4urrent is produced in a conductor when it is moved through a magnetic field because the magnetic lines of force are applying a force on the free electrons in the conductor and causing them to move. This process of generating current in a conductor by placing the conductor in a changing magnetic field is called induction. This This is called called induct induction ion be becau cause se there there is no physica physicall conne connecti ction on be betwe tween en the conductor and the magnet. The current is said to be induced in the conductor by the magnetic field. 8ne re#uirement for this electromagnetic induction to ta"e place is that the conductor which is often a piece of wire must be perpendicular to the magnetic lines of force in order to produce the maximum force on the free electrons. The direction that the induced current flows is determined by the direction of the lines of force and by the direction direction the wire wire is moving in in the field. In the animation animation above the ammeter (the instrument used to measure current) indicates when there is current in the conductor.

If an A4 current is fed through a piece of wire the electromagnetic field that is produc produced ed is consta constantl ntlyy growi growing ng and shrin" shrin"in ingg due to the consta constant ntly ly changi changing ng current in the wire. This growing and shrin"ing magnetic field can induce electrical

current in another wire that is held close to the first wire. The current in the second wire will also be A4 and in fact will loo" very similar to the current flowing in the first wire. It is common to wrap the wire into a coil to concentrate the strength of the magnetic field at the ends of the coil. %rapping the coil around an iron bar will further concentrate the magnetic field in the iron bar. The magnetic field will be strongest inside the bar and at its ends (poles).

9en6:s 9aw1 %hen an emf is generated by a change in magnetic flux according to !araday:s 9aw the polarity of the induced emf is such that it produces a current whose magnetic field opposes the change which produces it. The induced magnetic field inside any loop of wire always acts to "eep the magnetic flux in the loop constant. In the examples below if the 5 field is increasing the induced field acts in opposition to it. If it is decreasing the induced field acts in the direction of the applied field to try to "eep it constant.

Applications o! electromagnetic Induction Electrical "enerator:

The E'! generated by !araday:s law of induction due to relative movement of a circuit and a magnetic field is the phenomenon underlying electrical generators. %hen a permanent magnet is moved relative to a conductor or vice versa an electromotive force is created. If the wire is connected through an electrical load curr curren entt will will flow flow and and thus thus elec electr tric ical al ener energy gy is gene genera rate ted d conv conver erti ting ng the the mechanical energy of motion to electrical energy

Electrical trans!ormer

The The E'! E'! pred predic icte ted d by !ar !araday aday:s :s law law is also also respo esponnsib sible for for ele electric trical al transformers. %hen the electric current in a loop of wire changes the changing current creates a changing magnetic field. A second wire in reach of this magnetic field will experience this change in magnetic field as a change in its coupled magnetic flux d  ;  ;5 < d t . Therefore an electromotive force is set up in the second loop called the induced E'! or transformer E'!. If the two ends of this loop are connected through an electrical load current will flow.

Magnetic !lo# meter:

!araday:s law is used for measuring the flow of electrically conductive li#uids and slurries. $uch instruments are called magnetic flow meters. The induced voltage D generated in the magnetic field 5  due  due to a conductive li#uid moving at velocity v  is  is thus given by1

where = is the distance between electrodes electrodes in the magnetic flow meter.

!araday>s 9aw of Electromagnetic Induction first observed and published by 'ichael !araday in the mid& nineteenth century describes a very important electro&magnetic concept. Although its mathematical representations are cryptic the essence of

!araday>s is not hard to grasp1 it relates an induced electric potential or voltage to a dynamic magnetic field. This concept has many far&reaching ramifications that touch our lives in many ways1 from the shining of the sun to the convenience of mobile communications to electricity to power our homes. %e can all appreciate the profound impact !araday>s 9aw has on us.

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principles o! electromagnetic induction are applied in man& devices and s&stems' including: •

Electrical generators

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Induction motors

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Induction sealing

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Inductive charging

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Transformers

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%ireless energy transfer

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