XI Physics Manual

14. Take three readings & find the mean value. 15. Repeat the same procedure to measure the diameter of one more object. Observations: 1) Smallest division on main scale = S = …………………. cm.

Calculations: 1. The radius of the Steel ball R =

DB 2

2. The volume of the Steel ball V =

4 π R3 3

2) Total Number of divisions on the C.S. = N = ……………….. 3) Least Count ( L.C.) of Micrometer Screw Gauge = S / N = …………cm. 4) Zero error Z = ± r x L.C.

= ………………..cm.

Results: 1. Mean diameter of Steel ball DB = …………………….. cm 2. Mean diameter of spoke Ds = ………………………cm

Observation Table:

3. Volume of ball V = …………………..cm Name of Object

Obs. No.

M.S.R. a cm.

Circula r Scale Div b

Circular Scale Reading b x L.C.= c cm

Total Reading a + c cm

Mean Diameter cm

Experiment No. 1

1 Steel Ball

2

DB =

3 1 Spoke

2 3

Title:

Use of Vernier Calipers.

Aim:

To measure the length, Breadth and Height of a wooden block Vernier Calipers.

Ds = Apparatus:

Diagram:

Vernier Calipers, Wooden block etc.

Obs. No.

M. S. R. a cm

Vernier div b

Vernier scale Reading b x L.C.= c cm

Total Reading a + c cm .

Mean length L cm

1

5. Repeat the above procedure for breadth and height of the block. Observations: 1) Smallest division on main scale = S = …………………. cm.

2

2) No. of divisions on vernier scale = N = ………………..

3

3) Least Count ( L.C.) of vernier calipers = S / N = ………………..cm.

Observation Tables: 1). For Length of wooden box.

Obs. No.

M. S. R. a cm

Vernier div b

Vernier scale Reading b x L.C.= c cm

Total Reading a + c cm

Mean breadth B cm

1 2 3

2). For breadth of wooden box.

Procedure: 1. Note the smallest division on main scale and the total number of divisions on the vernier scale N. Hence find the least count of the vernier. 2. Hold the woodwn box between the jaws of vernier calipers. Note the position of Zero of vernier scale on the main scale (a). Note the vernier division (b) that coincides with some division on main scale. 3. Calculate total reading for the length of the wooden block. 4. Take two more observations for the same body.

3). For height of wooden box

Obs. No.

M. S. R. a cm

Vernier div b

Vernier scale Reading b x L.C.= c cm

Total Reading a + c cm

Mean height H cm

1 2

Procedure: 1. Note the smallest division (S) on the main scale of the micrometer screw. 2. Note the total number of divisions (N) on the circular scale of micrometer screw. 3. Hence find the least count of micrometer screw gauge L.C. = S / N.

3

4. Close the jaws of micrometer screw lightly and note the C.S. divisions on the reference line (r div.). Calculate zero error (Z) as Z = ± r x L.C. 5. If zero division of C.S. coincides with the reference line on main scale, then there is no zero error. 6. If zero division of C.S. does not coincide with the reference line on main scale, then there is error in the instrument. Results:

Length of the wooden block L = ………………….. cm.

Height of the wooden block H = ………………….. cm.

7. If zero division of C.S. is ahead of zero on M.S., then the zero error is positive. If ‘r’ is the division of C.S. coincides with the reference line of M.S., then the zero error is positive.

Precautions: 1) Just hold the object between the jaws of vernier calipers without pressing it too hard. 2) Take readings at different positions of the body.

8. If zero division of C.S. is behind the zero of on M.S., then the zero error is negative. If ‘r’ is the division of C.S. coincides with the reference line of M.S., then the zero error is negative.

Breadth of the wooden block B = ………………….. cm.

Experiment No. 2 Title: Use of Micrometer Screw Gauge. Aim: To measure the diameter of objects using a Micrometer Screw Guage. Appratus: Micrometer Screw Gauge, objects of different diameters. Diagram:

9. If the zero error is positive then subtract & if negative then add in the circular scale reading. 10.Hold the object whose diameter is to be measured between the jaws of micrometer screw with light pressure. Note the main scale division (a) seen on the main scale rod. 11.Note the C.S. division (b) which coincides with the reference line on M.S.. 12. Calculate the total reading. 13. Correct the total reading by adding or subtracting the zero error.

6. Complete the parallelogram ABCD Measure the diagonal AC and determine the magnitude of R using the scale chosen. This give the value of R by geometrical method.

7. Also measuring ∠ BAD = θ, and using formula calculate R.

Aim:

Apparatus:

8. Repeat the above procedure for another unknown weight.

Formula:

Observation Table: Obs No

P gm wt

Q gm wt

To find radius of curvature of a spherical surface by using spherometer.

Θ

R=diagonal AC gm wt

R by calculation gm wt

R by direct Measurement gm wt

Spherometer, Spherical surface, plane mirror, ruler.

R =

a2 6h

+

h 2

where R = Radius of curvature of spherical surface

a = Average distance between two legs of spherometer h = Sagitta of curved surface.

Diagram:

1 2 3 4 5 Procedure:

Results: 1. Unknown weight R by geometry = …………………. gm wt. 2. Unknown weight R by calculation = …………………. gm wt.

Experiment No. 5 Title:

Coefficient of static friction

Aim: To determine the coefficient of static friction µ s. Apparatus: A horizontal plane, Wooden block, spirit level, string, known weights, pan etc. Diagram:

Experiment No. 3 Title:

Use of Spherometer

1. Take the impressions of three legs of spherometer on paper. Measure the distances between the legs as three sides a1, a2, a3. Hence find the average distance between the legs. 2. Find the least count ( L. C. ) of spherometer. 3. Keep the spherometer on the plane mirror and move its screw till the tip of the screw just touches the plane mirror i.e. when the tip touches the tip of its image in the plane mirror. 4. Note the division of main scale (a) which is just below the upper surface of C.S. 5. Note the circular scale division (b) which coincides with the surface of main scale. 6. Find the total reading as T. R. = a x ( b x L.C. ) 7. Repeat three times and hence find the mean total reading (X). 8. Keep the spherical surface on the plane mirror; keep spherometer on the spherical surface so that all the legs are in contact with the spherical surface and the tip of the screw just touches the centre of the spherical surface. Note spherical reading. Repeat three times and find the mean spherical surface reading ( Y). 9. Repeat the above procedure three times & find the mean total reading (Y). 10. Find sagitta of spherical surface as h = Y - X. 11.Hence calculate the radius of curvature R of the spherical surface.

Observations: 1. a1 = ……………..cm, a2 = ……………..cm, a3 = ……………..cm,

a +a +a ∴ a = 1 2 3 = ……………..cm 3

Title:

Law of parallelogram of forces.

Aim:

To find the weight of a body using the Law of parallelogram of forces.

Apparatus:

2. Smallest division on main scale of spherometer = S = …………..cm 3. No. of divisions on circular scale of spherometer = N = ……….. …

Formula:

Observation Tables: Obs. No

M.S.R. a cm

Vernier div. b

Ver. Scale Reading b x L.C.= c cm

Total Reading a + c cm

1

Mean Diameter cm

Sigatta y - x =h cm

R = (P2 + Q2 + 2PQ Cos θ)½ Where R P Q Θ

4. L. C. of spherometer = S / N = ………………cm

Surface

A wooden board with two pulleys fixed on it, known weights, unknown weights, plane mirror, paper etc.

= = = =

Magnitude of the resultant force R. Magnitude of the force P. Magnitude of the force Q. Angle between P & Q.

Diagram::

x=

2 3 1 Spherical surface

y =

2 3

Calculations: 1. Sagitta of spherical surface = h = y - x 2. Radius of curvature of spherical surface R =

a2 6h

+

h 2

Procedure:

Result:

1. Fix the board with pulleys in vertical position. Fix a paper on it.

The radius of curvature of spherical surface R = …………………..cm

2. Pass a string over the two pulleys. The another string at Centre of the string.

Precautions: Consider the bottom reading on main scale as zero, the middle as 1 cm =10 mm and the top as 2 cm = 20mm. In this way all readings are positive.

Experiment No. 4

3. Attach known weight P & Q gm wt, to both the ends passing over the two pulleys and known weight R at the end of second string. Adjust weights P & Q so that the system weights P, Q and R are in equilibrium. Note the weight at the centre as R. This is the value of R by direct measurement. 4. Using plane mirror mark the directions of P & Q on the paper. For this hold the plane mirror behind the strings on the paper and mark points on the paper when the string and its image in the plane mirror coincide.

5. Draw the lines showing directions of P & Q meet at point A on paper. With suitable scale mark the points B & D along the lines, so that AB and AD represent the magnitudes of P and Q respectively.

Result: The R. I. of given liquid = n = ……………………..

Formula:

R r where R is the vertical distance between the pin and the pole of the concave mirror without liquid. (Fig. 1) and r is the vertical distance between the pin and pole of the concave mirror when the liquid is present. Refractive Index of a liquid = n =

Procedure: 1. Place the concave mirror on a horizontal surface. Hold an index pin horizontally above the concave mirror with the help of retort stand. The tip of the pin should be on the axis of the mirror. 2. Observe the image of the pin from a suitable distance along the axis. 3. Adjust the position of the pin such that there is no parallax between the pin and its image. This can be achieved by moving the pin in the upward or downward direction.

Procedure: 1. Find weight of wooden block (W0) and weight of empty scale pan (P 0). Level the horizontal plane by using a spirit level. Keep the wooden block on the horizontal surface. Tie a string tp the wooden block, pass it over the pulley and attach a scale pan to it. 2. Adjust the pulley so that the string is perfectly horizontal and take care to see that the scale pan hangs freely without touching the table. 3. Keep suitable weights in the scale pan so that the block just starts moving. Take two observations for the same load W. Note mean effort required to move the block (P). 4. Repeat for five different loads (W1) by changing weights on the block and find the corresponding efforts (F) to just move the block in each case. Find mean coefficient to static friction.

Observations:

4. Measure the distance R between the pin and pole of the mirror.

1. Weight of the wooden block = W0 = ……………….. gm wt.

5. Repeat the adjustment described in step No. 3 and measure R for two more times.

2. Weight of the empty scale pan = P0 = ……………….. gm wt. Observation Table:

6. Now pour a small quantity of the liquid on the reflecting surface of the concave mirror. 7. Adjust the position of the pin such that there is no parallax between the new position of the pin and its image (Fig. 2).

Obs No

8. Measure the distance r between the pin and the pole of the mirror.

1

9. Repeat the adjustment as described in step No. 7 and measure r for two more times.

2

Wt on Block W1 gm wt

Total Load W=W0+W1 gm wt

Wt in Scale pan P gm wt Mean I II P

Total Effort P=P0+P

µ

s

P W

=

Mean

µ

s

3 4

Observation Table: Sr. No. Distance

i

ii

iii

Avarage Value

Unit

1

R

cm

2

r

cm

Graphs:

1. Plot a graph of P versus W & find the slope. 2. Plot a graph of P versus W1 (wt on the block) to get weight of the block from the graph.

P

Slope =

0

W

µ

P

s

W0

0

Slope =

µ

s

W1

1. Determine approximate focal length of a convex lens by using the distant object method. 2. Keep the distance D between illuminated object and screen more than 4 f. Measure it in cm. 3. Place a convex lens in between the object and screen. There are two positions of lens when we get once magnified and once diminished image on the screen. Mark the two positions of lens. Measure the distance between those two positions of lens as d. 4. Repeat this procedure for five values of D. Increase D by 10 cm. Observations: Approximate focal length of convex lens = ……………cm.

Results: 1. µ

s

by observation =

2. µ

s

by graph =

3. Weight of the block by graph W0 = …………….. gm. wt.

Experiment No. 6

Obs. No 1

D+d cm

D–d cm

4D cm

3

Determination of focal length of a convex lens.

4

Aim:

To determine focal length of a convex lens by the displacement method.

5

Illuminated object, convex lens, screen, scale etc.

D cm

2

Title:

Apparatus:

D cm

6

Diagram:

Formula:

Procedure:

( D + d )( D − d ) 4D where F = Focal length of the convex lens. D = Distance between the screen & object. d = Distance between the two positions of lens.

F =

Calculations:

( D + d )( D − d ) 4D Result: Focal length of a given convex lens = F = ……. cm. F =

F cm

Precautions: 1. See that the images formed on the screen are sharp. 2. Don’t change the distance D for the same set of readings.

Observation Table:

Experiment No. 7 Title:

Refractive Index (R.I.) of liquid by a concave mirror.

Aim:

To determine the refractive index of a liquid using a concave mirror.

Apparatus:

Concave mirror, liquid, retort stand, pin and scale.

Diagram:

Fig. 1

Fig. 2

Experiment No.10 Title: Prism I. Angle of prism. Aim: To determine angle of prism. Apparatus: Prism, Paper, Pins, Drawing pins, wooden board etc.

Procedure: 1. Fix the paper on the drawing board with the help of drawing pins. Place the prism. Mark the outline of the prism ABC. Mark the base BC by inclined lines. 2. Remove the prism. Draw two lines PQ and WX parallel to each other and perpendicular to BC. 3. Fix two pins P & Q on the straight line PQ. Place the prism. Looking into the face AB fix two more pins R & S so that reflected images P & Q and R & S appear to be in the same straight line. Mark the positions of the pins, after removing them and the prism. 4. Now fix two pins W & X on the straight line WX. Place the prism in its position. Looking into the face AC fix two more pins Y & Z such that the refracted images of W & X and the pins Y & Z appear to be in the same straight line. Remove the prism & pins. Mark the positions of the pins.

Experiment No. 8

Ray Diagram: Title:

To determine unknown resistance by Ohm’s law.

Aim:

To determine unknown resistance of the coil of a wire by using Ohm’s law.

Apparatus: Obs. No. 1 2 3 4

2A º

Mean 2A º

Angle of Prism A º

A small electric bulb or a coiled wire, an accumulator, rheostat, ammeter A, voltmeter V, Plug key, connecting wires etc. Circuit Diagram:

Formula:

V I V = Potential drop across the unknown resistance. I = Electric current and R = Unknown resistance. ∴ R =

V = IR where

Procedure: 1. Connect the apparatus as shown in the circuit diagram. 2. Adjust the rheostat such that small measurable current passes through the circuit. 3. Measure the potential difference in Volts with the voltmeter across the unknown resistance. 4. Measure the current passing through the circuit as indicated by the ammeter. 5. Change the rheostat in equal steps and record the ammeter and voltmeter readings. Observation Table:

Graph: Plot a graph of potential drop V (Y-axis) against current I (X-axis). The graph is a straight line in accordance with Ohm’s law.

Glass

Water

Formula: R. I. of glass or water =

Real Depth Apparent Depth

=

R A

Procedure: 1. For Glass Slab: 1. Determine the L.C. of the vernier scale on a travelling microscope. 2. Keep the microscope in vertical position. Adjust the eyepiece so that the cross-wires are easily seen. 3. Fix a small piece of paper below the microscope. Mark a dot or a line or a cross on it. For this use rack & pinion arrangement. Don’t isturb the Sr. No.

Current Potential drop Unknown Resistance R I amp V volts Ω . [ R = V / I]

Mean R Ω.

1 2 3

V

Slope = R

4 5 adjustment throughout the experiment.

Results:

I 1. Unknown resistance R =

……………. Ω .

2. R from graph = slope = ………………Ω .

Experiment No. 9 Title: Refractive Index (R.I.) of glass and liquid. Aim: To determine the refractive index of glass and liquid using a travelling microscope. Apparatus: Travelling microscope, glass slab, saw dust, Beaker, water, coin or pin. Diagram:

Focus the microscope on the mark you have made. Note the reading on the microscope X cm. 4. Place a glass slab on the mark. Focus the microscope on the same mark by moving the microscope upwards. Now you are viewing the refracted image I of the object O. Note the microscope reading Y cm (Y > X). 5. Sprinkle some saw dust on the surface of the glass slab. Raise the microscope further till the saw dust is in focus. Note the microscope reading Z cm (Z>Y). 2. For Liquid: 1. Place the beaker on the table. Drop a pin or a coin in it which serves as the object. Adjust the microscope till the object is in focus. Note the microscope reading X cm.

2. Pour some water (2-4 cm in height) in the beaker. Raise the microscope till the coin is in focus. Note the microscope reading Y cm (Y>X). 3. Sprinkle some saw dust on the surface of water. Raise the microscope till the saw dust is in focus. Note the microscope reading Z cm (Z>Y). Observations: 1. Smallest division on main scale = S = …………..cm 2. Total No. of divisions on vernier scale = N = ……….. … 3. L. C. of travelling microscope = S / N = ………………cm Observation Table: Real Depth Apparent Depth

Calculation:

R. I. =

Result:

1. R.I of Glass = …………………

Microscope reading when focus on Object Image Saw Dust X cm Y cm Z cm

Obs. No.

Real Depth (Z - X) cm

Apparent Depth (Z – Y) cm

1

2. R.I. of Water = …………………..

Glass 2 1 Water 2

5. Join SR & YZ and produce them to intersect at D. Measure angle SDZ which is 2A. 6. Take four readings of 2A . Find the mean value of 2A & hence find A. Result: Angle of prism = A = ……….. º.

Experiment No.11 Title: Prism II. Angle of Deviation. Aim:

To determine angle of deviation & refractive index of prism.

Apparatus:

Prism, Paper, Pins, Drawing pins, wooden board etc.

Ray Diagram:

n =

 A + δm  Sin   2   A Sin  2

Procedure: Observation Table: Given : Angle of prism = A =

……….. º. ( From Expt. No. 10)

Graph: δ

δm

1. Keep the prism on the paper and draw its outline ABC. Remove the prism. Mark its base BC by inclined lines. Draw a normal to the face AB at E, nearly a midpoint of AB. At E draw another line SR making an angle i = 30º with the normal. Fix Obs. No. Angle of incidence Angle of deviation two pins P & Q on the i deg. δ deg. line PQ. 35 2. Place the prism in its 40 position. Now 45 looking through 50 the face AC fix two 55 more pins R & S such 60 that the refracted images of P & Q and the pins R & S appear to be in the same straight line. Mark the position of the pins. Remove the prism and pins. 3. Join SR and produce it to meet at O. PQ is the incident ray. RS is the emergent ray. Measure the angle between these two rays which is angle of deviation δ. 4. Repeat this for 35º, 40º, 45º, 50º, 55º and 60º and so on. 5. Plot the graph of δ against i. hence find δm. 6. Calculate R.I. of prism by prism formula. Result:

(i = e) Formula:

i

Refractive index of the material of prism = n = …………………