JOHNSON GRAMMAR SCHOOL, I.C.S.E.& I.S.C

Mallapur, Hyderabad-76

10TH CLASS Physics – ( 2021-22)

Lab manual observations AP018 As a result of the pandemic situation, we are unable to conduct a the practical for the year 2021-22. But, as a

measure of preparedness, we are circulating the lab manual content. We expect that the students to completed

writing it in their lab manuals by end of the puja vacation. Additionally, we are also circulating readings for the experiments and expect that this too will be populated in

the lab manuals of all students.

The sheets given below have the following content :

• Content , Observations, and diagrams of 10 practicals.

• Each practical to be written on a new page.

• Each Practical has content (to be written on the ruled side of the lab manual) and observations table

with the readings and diagram (to be written or drawn on the unruled side of the given practical

manual)

• The diagram to be drawn on the first unruled side and the observations on the next unruled side.

• The result of each experiment is given alongside

• Graphs for certain experiments are also attached (copy the graph on a graph sheet, which is given at

the back side of the lab manual, and attach it to the lab manual) *Students are to submit their completed lab manuals (with observations) physically to the school the date

for which will be informed to you through portal.

*The lab manual is the project work in physics and will be allotted marks out of 20 marks.

P.T.O

1.MA Of a First Order Lever

Aim: To determine the mechanical advantage of a first order lever.

Material required:

A half metre scale, Weights, Retort stand, thread and hangers.

Theory:

• Levers work on the principal of moments which states that:

Clockwise moments of load about fulcrum = Anti-clockwise moments of effort about the fulcrum

𝑳𝒐𝒂𝒅(𝑳) 𝒙 𝒍𝒐𝒂𝒅 𝒂𝒓𝒎(𝑳𝑨) = 𝑬𝒇𝒇𝒐𝒓𝒕(𝑬) 𝒙 𝒆𝒇𝒇𝒐𝒓𝒕 𝒂𝒓𝒎(𝑬𝑨)

• Mechanical advantage of a lever is the ratio of the load to the effort.

MA = 𝑳𝒐𝒂𝒅 (𝑳)

𝑬𝒇𝒇𝒐𝒓𝒕 (𝑬) =

𝑬𝒇𝒇𝒐𝒓𝒕 𝑨𝒓𝒎(𝑬𝑨)

𝑳𝒐𝒂𝒅 𝑨𝒓𝒎 (𝑳𝑨)

Procedure:

1. Balance the half-meter scale by suspending it through a thread to a retort stand.

2. Adjust the position so that the scale balances horizontally and note the centre of gravity.

3. Keeping the C.G position, same suspend two known weights on either sides of the scale and adjust

the position of the weights so that the scale is in equilibrium.

4. Note the perpendicular distances from the two weights to the C.G.

5. Follow the same procedure using different weights.

Precautions:

1. Centre of gravity should not be altered.

2. While noting the perpendicular distances the scale should be balanced.

Result:

Mechanical Advantage of the first order lever can be >1,<1 or =1.

Diagram and observations :(to be done on the unruled side of lab manual)

Observation table:

S.No Load (L)

gf

Effort (E)

gf MA=

𝑳

𝑬

Effort Arm (EA)

cm

Load Arm (LA)

cm MA =

𝑬𝒇𝒇𝒐𝒓𝒕 𝒂𝒓𝒎

𝑳𝒐𝒂𝒅 𝒂𝒓𝒎

1

50 50 1 17 18 0.9

2

150 100 1.5 12 8 1.5

3 100 150 0.67 12 20 0.6

___________________________________________________________________

Experiment No.2

Laws of refraction

Aim: To verify laws of refraction and to show that with increase in angle of incidence lateral displacement

increases.

Material required:

A drawing board, rectangular glass slab, pins, sheet of white paper, a protractor and sharply pointed pencil.

Theory:

The laws of refraction states that :

1. Incident ray, the refracted ray and the normal at the point of incidence lie on the same plane

2. The ratio sine of angle of incidence and the sine of angle of refraction for a pair of media is a constant.

µ = 𝐬𝐢𝐧 𝒊

𝐬𝐢𝐧 𝒓

Procedure:

1. Fix a sheet of white paper on the drawing board with the help of drawing pins at the four corners of the

sheet.

2. Place a glass slab on the paper and mark its boundary A1B1C1D1 with a fine pencil.

3. Remove the glass slab. Draw any line AO1 making an angle of 300 with the normal MO1N.

4. Put the glass slab back in position on the boundary line. Fix two pins P1 and Q2 vertically on the line

AO1 at least 5cm apart- and one pin close to the slab.

5. Look for the image of these pins in the slab from the opposite side C1D1 and fix two pins R1 and S1 so

that they are in the line with the image of P1 and Q2 as seen through the slab and at least 5cm apart.

6. Join the pricks of R1 and S1 to obtain the emergent ray. Draw a normal to M1N1 at the point O2.

Join O1O2 to get the refracted ray.

7. Measure the angle of incidence and angle of refraction. Produce AO1forward and draw a perpendicular

from emergent ray on the extended incident ray.

8. Measure the lateral displacement and repeat the experiment with different angles of incidence.

Precautions:

1. Angles to be measured accurately.

2. Encircle the points to mark the points marked by pins clearly.

Result:

1. The incident ray, refracted ray and normal lie on the same plane at point of incidence.

2. sin 𝑖

sin 𝑟= µ (constant) = _____1.46____________

3. Lateral displacement increases with increase in angle of incidence.

Diagram and observation: :(to be done on

the unruled side of lab manual)

Observation table:

S.No Angle of

incidence

Angle of

refraction

Sin I Sin r µ =

𝐬𝐢𝐧 𝒊

𝐬𝐢𝐧 𝒓

Lateral

displacement

1

300

200

0.5

0.3420

1.46

1.2cm

2

450

290

0.7071

0.4848

1.46

2 cm

• Mean value of refractive index µ = 𝟏.𝟒𝟔+𝟏.𝟒𝟔

𝟐 = 1.46

_______________________________________________________________

Experiment No.- 3

Angle of Prism

Aim: To find angle of prism by optical method.

Material required: A drawing board, few pins, a glass prism, a sheet of paper, a pencil and a protractor.

Theory :

The angle between the two refracting surfaces of a prism is called the angle of prism.

Procedure:

1. Take a sheet of white paper and fix it on the drawing board with pins.

2. Place a glass prism along its triangular base on the paper. Mark the boundary ABC of the glass prism

and then remove the prism.

3. Draw two perpendicular lines XY and X’Y’ from the base of the prism cutting the two refracting

surfaces AB and AC respectively.

4. Place two pins P and Q on the incident ray XY .

5. Place back the prism on the outline and observe the image of the pins from the same refracting surface

AB.

6. Place two more pins R and S in such a way that all appear in a straight line. Draw a line through the

marked points extending into the prism.

7. Follow the same procedure for incident ray X’Y’ on refracting surface AC and obtain the emergent ray

by marking point GH.

8. Extend the emergent ray inside the prism such that the rays RS and GH meet at a point O.

9. Measure angle SOH. The angle measured is twice the angle of prism.

Precautions:

1. Use a sharp pencil to draw boundary of the prism and rays of light.

2. The pins should have sharp tip and should be fixed exactly vertical to the plane of the paper.

3. The distance between the pins should be atleast 6 cm. It provides the greater accuracy in finding the

direction of incident ray and emergent ray.

Result :

Angle of prism A = ___600_____

Diagram and observation: (to be done on the unruled side of lab manual)

3. To find angle of prism by optical

X X’

Y Y’

Observation table:

S.No Angle SOH ½ Angle SOH (angle of prism)

1

1200 600

2

1200 600

Mean of angle of prism = = 𝟔𝟎+𝟔𝟎

𝟐 = 600

___________________________________________________________________

Experiment No.-4

Refraction through a prism

Aim: To trace the ray of light through a glass prism.

Materials required:

A Glass prism, Drawing board, PaperPins, Scale, Pencil and Protractor.

Theory:

• When light ray passes through a prism it refracts and bends towards the base. The angle between the

incident and emergent ray is called angle of deviation.

• The relation between the angle of incidence(i), angle of emergence (e), angle of prism(A) and angle of

deviation (D) is given by the following expression

𝒊 + 𝒆 = 𝑨 + 𝑫

Procedure:

1. A paper is fixed on the drawing board placed on the table.

2. Place the given glass prism on the paper and using the pencil, mark the outline ABC of the prism on the

paper.

3. Remove the prism, and using the scale and pencil, normal NN’ is drawn to the face AB at the point E.

4. Using the protractor, measure an angle 30° from the normal and draw a line PE making an angle 30° with

normal.

5. Fix two pins P and Q on this line place back the prism on the outline.

6. Viewing the pins from the face AC of the prism, two other pins R and S are fixed so that P, Q, R and

S are in a line. Later remove the pins.

7. A line SF is drawn to meet on the face AC through the marks of R and S and draw a normal through

point F.

8. Extend the line PE and SF backwards to meet at point G.

9. Measure angles MFS (angle of emergence) and HDS (angle of deviation).

10.Repeat the experiment for another values of angle of incidence (i) and the corresponding angle

of deviations is measured.

Precautions:

1. Angle of incidence should be between 30° and 50°.

2. Prism should not be disturbed.

3. Pins should be in vertical position.

Results:

1. The relation └A + └D =└i + └e is verified.

Diagram and observation: (to be done on the unruled side of lab manual)

Observation table:

Angle of prism = 600

____________________________________________________________

Experiment No.-5

Focal length and magnification of convex lens

Aim: To measure the focal length and magnification of a converging (convex lens).

Material required :

A convex lens and stand, A screen , A candle and a meter scale.

Theory:

S.No Angle of incidence (i) Angle of emergence (e)

Angle of deviation (D) i + e = A + D

1

500

620

500

500+620~ 500+600

2

600

750

700

600+750~ 700+600

• Light rays parallel to principal axis when incident on a convex lens ,after refraction converge to a point called

focus.

• The distance between the optic centre and focus is called focal length.

• If u is object distance from lens and v the image distance from lens then the focal length f is determined by

using the formula: 𝟏

𝒇 =

𝟏

𝒗 -

𝟏

𝒖

• Magnification of lens m = 𝑰𝒎𝒂𝒈𝒆 𝒅𝒊𝒔𝒕𝒂𝒏𝒄𝒆 (𝒗)

𝑶𝒃𝒋𝒆𝒄𝒕 𝒅𝒊𝒔𝒕𝒂𝒏𝒄𝒆 (𝒖)

Procedure :

1. Find the approximate focal length by focusing an image of a distant object onto a screen. The distance from the

object to the lens is its focal length.

2. Set up the equipment as in the diagram. The illuminated object should be a distance from the lens greater than

the rough length found in step 1.

3. Adjust the position of the cardboard screen until the image of is the sharpest focus possible

and most clearly visible on it.

4. With a metre stick, measure the distance u (from the candle to the centre of the lens) and then measure the

distance v (from the real image on the screen to the centre of the lens). Record these values.

5. Change the value of u and repeat steps 3 and 4. Do this at least four more times. Some values of u should be

chosen to give a diminished image and some to give a magnified one.

6. Now use the formula 1/v- 1/u = 1/f to determine focal length of lens.

7. Find the magnification using m = v / u

Precautions:

1. Repeat the experiment a number of times,

2. Make sure the image is in clear and sharp as possible.

3. Screen and lens are vertical and along a straight line.

Result:

1. Focal length of convex lens by distant object method =____10 _________cm

2. Mean value of focal length f by lens formula = 9.93 cm

3. Magnification of convex lens can be > 1, <1 and equal to 1.

4. Diagram and observation: (to be done on the unruled side of lab manual)

5.

6.

7.

8.

9.

Observation table:

S.No Object distance (u) cm Image distance (v) cm Magnification m =

𝒗

𝒖 Focal length f =

𝒖 𝒙 𝒗

𝒖+𝒗 cm

1

15 24 1.6 9.23

2

20 21 10.5 10.24

3

25 16 0.64 9.75

4

30 15.5 0.57 10.21

5

35 14.5 0.41 10.25

• Mean value of focal length f = 𝟗.𝟐𝟑+𝟏𝟎.𝟐𝟒+𝟗.𝟕𝟓+𝟏𝟎.𝟐𝟏+𝟏𝟎.𝟐𝟓

𝟓 = 9.93 cm

___________________________________________________________________

Experiment No.-6

Specific heat capacity of a solid

Aim: To determine the specific heat capacity of a solid.

Material required:

A Calorimeter with stirrer,a spring balance, A Thermometer, a solid, a tripod stand, Burner, A water bath.

Theory:

• Specific heat capacity of a solid is defined as the amount of heat required by the solid to show a rise in

temperature by 1K.

• When two substances of different temperature are mixed together, transfer of heat takes place till both

the bodies acquire equilibrium temperature.

Heat lost by a hot body = Heat gained by a cold body

Procedure:

1. Fill the beaker about half way with water and start heating it.

2. Weigh the solid metal, and then lower it into the beaker of hot water by means of a thread.

3. While the solid is being heated, weigh the inner chamber of calorimeter and the stirrer, together.

4. Fill the inner chamber of the calorimeter about half way with cool water and weigh it again.

5. Place the inner chamber of the calorimeter into the calorimeter jacket and place the lid on, then record the

temperature of the cold water.

6. Record the temperature of the hot solid when the temperature becomes steady.

7. Now quickly transfer the solid from the hot water to the calorimeter without splashing any water.

8. Place the lid onto the calorimeter and stir the water very gently and record the final equilibrium

temperature

Precautions:

1. Thermometer temperature to be recorded carefully.

2. Water should not splash while placing the solid into the calorimeter.

3. The lid of calorimeter should be closed as soon as the solid is placed in the calorimeter.

Result:

Specific heat capacity of the solid is = __0.4 J g -1 0 C -1

Diagram and observation: (to be done on the unruled side of lab manual)

Observations:

1.Mass of calorimeter + stirrer (m1) 30g

2.Mass of calorimeter + stirrer + water ( m 2) 50g

3. Mass of water ( m3) = m2- m 1 20g

4. Initial temperature of cold water ( T1) 25 0C

5. Mass of solid ( m ) 30g

6. Initial temperature of hot solid ( T2 ) 70 0C

7. Final temperature of mixture ( T ) 30 0C

8. Specific heat capacity of water ( c w ) 4.2 J g-1 0C-1

9. Specific heat capacity of calorimeter ( c c) 0.4 J g-1 0C-1

Calculations:

Heat gained by calorimeter and water = Heat lost by solid

𝒎𝟏 × 𝒄𝒄 × (𝑻 − 𝑻𝟏) + (𝒎𝟐 − 𝒎𝟏) × 𝒄𝒘 × (𝑻 − 𝑻𝟏) = 𝒎 × 𝒄 × (𝑻𝟐 − 𝑻)

𝒄 = 𝒎𝟏× 𝒄𝒄 × (𝑻−𝑻𝟏)+(𝒎𝟐 − 𝒎𝟏)× 𝒄𝒘 × (𝑻− 𝑻𝟏)

𝒎 × (𝑻𝟐−𝑻) =

𝟑𝟎× 𝟎.𝟒× (𝟑𝟎−𝟐𝟓)+𝟐𝟎× 𝟒.𝟐 × (𝟑𝟎− 𝟐𝟓)

𝟑𝟎 × (𝟕𝟎−𝟑𝟎) = 0.4 J g -1 0 C -1

___________________________________________________________________

Experiment No.- 7

Melting point of Naphthalene

Aim: To determine the melting point of naphthalene using a heating curve.

Material required:

A test-tube, a thermometer, retort stand, a beaker, Burner, Tripod stand, naphthalene balls and stop clock

Theory:

Melting point of a substance is the temperature at which a solid changes into liquid at constant temperature.

Procedure:

1. Powder the naphthalene balls and place it in a test-tube.

2. Keep the thermometer inside the test-tube and clamp the test-tube to a retort stand. 3. Fill the beaker partially with water and place the test-tube inside it. 4. Heat the water with the burner. Note down the temperature after every 20 minutes with stop clock. 5. When naphthalene starts to melt the temperature becomes constant for some time. 6. Allow naphthalene to melt completely while measuring temperature. 7. Draw temperature v/s time graph to determine melting point of naphthalene.

Precautions:

1. Test –tube should not touch the sides or bottom of the beaker

2. Level of water in beaker should be more than the level of naphthalene in test-tube.

3. Packing of the powder should be uniform without any big air gaps in between the solid particles

Result:

Melting point of naphthalene is = _____79 0 C _________

Diagram , observation and graph (to be done on the unruled side of lab manual)

naphthalene

Observation table:

Graph on melting point of naphthalene

S.No Time (seconds) Temperature (0 C) S.No Time (seconds) Temperature (0 C)

1 0 52 0 C 8 210 71 0 C

2 30 55 0 C 9 240 74 0 C

3 60 58 0 C 10 270 76 0 C

4 90 61 0 C 11 300 79 0 C

5 120 63 0 C 12 330 79 0 C

6 150 66 0 C 13 360 79 0 C

7 180 68 0 C 14 390 82 0 C

___________________________________________________________________ Experiment No.-8

Resonance in Air Column

Aim: To verify that the frequency of sound emitted due to vibration in air column depends on its length.

Material required:

Two tuning forks, a measuring cylinder and a rubber hammer and a scale .

Theory:

• Resonance in an air column takes place when the natural frequency of air column becomes equal to the

forced frequency of the tuning fork.

• If the frequency of the tuning fork increases the length of the air column at which resonance is produced

decreases. ( 𝑓 𝛼 1

𝑙 )

Procedure:

1. Take a measuring cylinder and partially fill it with water.

2. Take a tuning fork and a rubber hammer and strike the tuning fork on the rubber hammer.

3. Place the vibrating tuning fork horizontally above the cylinder. Sound waves are passes down to the tube

and reflect back at the water surface to hear a mild sound.

4. Keep changing the level of water and keep the vibrating tuning fork on the mouth of the measuring

cylinder until one hears maximum sound.

5. Note down the length of air column in the measuring cylinder with a scale.

6. Follow the same procedure for the other tuning fork.

Precautions:

1. Slowly reducing the level of water in the measuring cylinder.

2. Tuning fork should not touch the mouth of the cylinder.

Result:

The length of the vibrating air column is inversely proportional to the frequency of the sound emitted.

Diagram and observation: (to be done on the unruled side of lab manual)

Observation table:

S.No Frequency of tuning fork (Hz) Length of air column (cm)

1

512 16

2

480 17.5

___________________________________________________________________

Experiment No.-9

Ohm’s Law

Aim: To verify Ohm’s law and determine the resistance of given resistor.

Material required :

Aunknown resistor, an ammeter, a voltmeter, battery eliminator, a plug key, rheostat and connecting wires.

Theory:

It states that the current (I) flowing through a conductor is directly proportional to the potential difference (V)

across it considering all physical conditions remains constant.

V α I

V = I x R ( R = Resistance)

Procedure :

1. Arrange the apparatus as per the circuit diagram.(given below)

2. Make the connections as per circuit diagram. All connections must tight. Take care to connect the

ammeter and voltmeter with their correct polarity.

3. Determine the zero error and least count of the ammeter and voltmeter and record them.

4. Adjust the rheostat to pass a low current.

5. Insert the key K and slide the rheostat contact to see whether the ammeter and voltmeter are showing

deflections properly.

6. Adjust the rheostat to get a small deflection in ammeter and voltmeter.

7. Record the readings of the ammeter and voltmeter.

8. Take atleastfive sets of readings by adjusting the rheostat gradually.

9. Plot a graph with V along y-axis and I along x-axis.

10. The graph will be a straight line which verifies Ohm's law.

11. Determine the slope of the V-I graph. The slope gives resistance of the wire.

Precautions :

1. All the electrical connections must be tight.

2. Voltmeter and Ammeter must be of proper range.

3. The key should be inserted only while taking readings.

Result:

1. Mean value of V/I from observations, R = _______2.6_______Ω

2. The Resistance from the slope of V v/s I graph = _____3___________Ω

Circuit Diagram and observation: (to be done on the unruled side of lab manual)

Ohm’s Law Observation sheet

Observations:

Least count of the given ammeter = .....10-2.......... A. Least count of the given voltmeter = ......0.05............V.

Series circuit

S.No Ammeter reading (A) Voltmeter reading (V) Resistance

R = 𝑽

𝑰 Observed A Corrected A Observed V Corrected V

1

8 0.08 4 0.20 2.5Ω

2

15 0.15 8 0.40 2.67 Ω

3

10 0.1 5 0.25 2.5 Ω

4

25 0.25 14 0.70 2.8 Ω

• Mean value of V/I from observations, R = 𝟐.𝟖+𝟐.𝟓+𝟐.𝟔𝟕+𝟐.𝟓

𝟒 = 2.6 Ω

Observation from graph:

______________________________________________________________ Experiment No.-10

Resistance in Series and Parallel

Aim: To determine the equivalent resistance in series and parallel circuit.

Material required :

Two unknown resistors, an ammeter, a voltmeter, a battery eliminator, a plug key, rheostat and connecting

wires.

Theory:

Series circuit- A circuit in which resistors are all arranged in a chain, so that the current has only one path to

take. The equivalent resistance in series circuit is

RS = R1 + R2 + R3

Parallel circuit – A circuit in which each resistor is connected in a separate path and receives the same voltage,

and the total circuit current is equal to the sum of the individual branch currents. The equivalent resistance in

parallel circuit is 𝟏

𝑹𝑷=

𝟏

𝑹𝟏 +

𝟏

𝑹𝟐 +

𝟏

𝑹𝟑

Procedure :

12. Arrange the apparatus for series as per the circuit diagram.(given below)

13. Make the connections as per circuit diagram. All connections must tight. Take care to connect the

ammeter and voltmeter with their correct polarity.

14. Determine the zero error and least count of the ammeter and voltmeter and record them.

15. Adjust the rheostat to pass a low current.

16. Insert the key K and slide the rheostat contact to see whether the ammeter and voltmeter are showing

deflections properly.

17. Adjust the rheostat to get a small deflection in ammeter and voltmeter.

18. Record the readings of the ammeter and voltmeter.

19. Take at least five sets of readings by adjusting the rheostat gradually.

20. Calculate the equivalent resistance using the formula. Repeat the procedure for parallel circuit.

Precautions :

4. All the electrical connections must be tight.

5. Voltmeter and Ammeter must be of proper range.

6. The key should be inserted only while taking readings.

Result:

1. Mean value of R in series circuit = _____2.2 Ω __________Ω

2. Mean value of R in parallel circuit = ____1 Ω __________Ω

Circuit Diagram and observation: (to be done on the unruled side of lab manual)

Observations:

Least count of the given ammeter = .....10-2.......... A. Least count of the given voltmeter = ......0.05............V.

Series circuit

S.No Ammeter reading (A) Voltmeter reading (V) Resistance

R = 𝑽

𝑰 Observed A Corrected A Observed V Corrected V

1

10 0.1 5 0.25 2.5 Ω

2

15 0.15 6 0.3 2 Ω

3

16 0.16 7 0.35 2.2 Ω

4

20 0.2 8 0.4 2 Ω

• Mean value of R in series circuit = 𝟐+𝟐.𝟐+𝟐+𝟐.𝟓

𝟒 = 2.2 Ω

Parallel circuit

S.No Ammeter reading (A) Voltmeter reading (V) Resistance

R = 𝑽

𝑰 Observed A Corrected A Observed V Corrected V

1

50 0.5 10 0.5 1 Ω

2

90 0.9 18 0.9 1 Ω

3

120 1.2 24 1.2 1 Ω

4

150 1.5 30 1.5 1 Ω

• Mean value of R in series circuit = 𝟏+𝟏+𝟏+𝟏

𝟒 = 1 Ω