Physics Paper 3 Questions and Answers - Bondo Mocks 2021 Exams

QUESTIONS

Question 1
You are provided with the following apparatus:

• Rectangular glass block
• Two plain papers
• Four optical pins
• Four paper pins or thumb pins
• Protractor
• Half meter rule

PART A
PROCEDURE:

1. Place the glass block on the plain paper on its largest area, trace it’s outline and mark it’s sides ABC and D. Mark the point P0 on the center of side BC as shown in Figure 1 below.
2. Measure the breadth of the glass block.
b =….……..cm (1 mark)
3. Replace the glass block and fix an object pin at P0 such that the pin lies along the surface of the glass block.
4. With your eye on the side AD closer to A, fix pins P1 and P2 such that they are in line with the image Pi of P0 as seen from the side AD through the glass block.
5. From the same side AD closer to D, fix pins P3 and P4 such that they are in line with the image Pi of P0 seen through the glass block.
6. Remove the glass block and join P1 and P2, and P3 and P4 to meet at Pi.
7. Join P0 to Pi and measure length P0Pi
P0Pi =…………………………………..m (1 mark)
8. Determine the ratio;       b       = n (2 marks)
b − P0Pi
(Hand in the outline with the question paper.) (1 mark)

PART B

1. Trace the outline of the glass block again on the second plain paper and label it ABCD as shown in Figure 2.
2. Construct a normal on the side AB approximately 3cm from A and measure angle of incidence i =35° (secure the plain paper using paper pins).
3. Replace the glass block on the outline and fix pins P1 and P2 along the line of 35°.
4. Viewing from the sides CD through the block, fix pins P3 and P4 such that they appear in line with the images of P1 and P2.
5. Join P3 and P4 and join x and y.
6. Extend the line P1 and P2 to obtain lateral displacement as shown in the figure and measure the lateral displacement d and angle r0.
8. Repeat the procedure in (i) to (vi) for angles of incidence 45°, 55°,65° and 75°.
(Hand in the plain paper on which you have done your experiment together with the exam paper) (2 marks)
 i0 35 45 55 65 75 r0 d(cm)
(5 marks)
9. Plot a graph of d(cm) against r0 (5 marks)
1. Determine the value r0 where the lateral displacement d equals to the breadth b of the block.
r0 = ……………………………………………………… (1 mark)
2. Given that k sin r0 = 1, determine the value of k (2 marks)

Question 2

PART A

• A glass beaker
• A metal solid
• Some water
• Source of Heat
• A piece of cotton thread
• A plastic beaker wrapped with tissue paper on the outside.
• A thermometer
• Liquid L
• Measuring balance to be shared

Proceed as follows:

1. Fill the glass beaker with the water provided and place it on the heat source.
Use the piece of thread to carefully lower the metal solid to the bottom of the beaker. Heat the water to its boiling point. Use the thermometer to measure its point.
Boiling point of water =………………………………Kelvin (1 mark)
2. Find the following measurements using appropriate instruments
Mass of the metal solid Ms = …………………………… g (½ mark)
Mass of the wrapped empty plastic beaker
M1………………………………g (1 mark)
Use the plastic beaker to measure 240ml of liquid L, hence find the joint mass of the plastic beaker and its content liquid L,
M2 =……………………………………………. g (½ mark)
Initial temperature of liquid L, T1 = …………………………………..Kelvin (1 mark)
3. At boiling point of water, quickly transfer the metal solid into liquid L, stir well and measure the temperature of the mixture immediately.
Temperature of the mixture
T2 = …………………………………. Kelvin (1 mark)
4. By using the measurements taken in parts (a), (b) and (c) as well as the equation provided below, determine the specific heat capacity of liquid L.
(Take S.H.C. of metal solid = 480Jkg-1k-1 and S.H.C. of plastic = 359 Jkg-1k-1)
(Heat lost by metal solid) = (heat gained by liquid L) + (heat gained by plastic beaker) (3 marks)

PART B

You are provided with the following apparatus:

• A nichrome wire
• A 20g mass
• A meter rule
• A test –tube
• A retort stand, boss, and clamp

Proceed as follows:

1. Measure the length, L, of the nichrome wire provided
L = ………………………. cm (½ mark)
2. Wind the whole length of the wire tightly on the test-tube making sure that the turns are as close as possible but not overlapping. Measure the length, β, of the coil made.
β =………………………………. cm (½ mark)
3. Remove the coil from the test-tube. Straighten the first and the last turns of coil. Bend one end to make a hook.
4. Count and record the number, N, of complete turns remaining on the coil.
N =……………… (1 mark)
5. Measure and record the distance h1 between the end turns of the coil as shown on the Figure 1 below.
h1= ……………………………………. (½ mark)
6. Load a 20 g mass on the coil as shown in Figure 2 above. Measure and record the distance, h2, between the end turns of the coil.
h2 = ……………………………………. (½ mark)
7. Determine the spring constant K in S.I units. (1 mark)
8. Obtain the constant, P, for the wire from the expression: (2 marks)
P = 4mgR³
Kr4
Where: m is the mass used, g is acceleration due to gravity (g = 10m/s2),
R =   L     and r =   β
2πN               2πN

PART C

You are provided with the following:

• Two cells
• A 2.5 V torch bulb in a bulb holder
• 10 Connecting wires
• Switch
• Ammeter (0 – 3A),
• Voltmeter (0 – 5 V)
• Two cell holders

PROCEDURE 1

SET UP ONE

Set up the circuit shown in figure above.

V1 ………………………………………………………………………….. (½ mark)
• Switch on the circuit.
2. Read and record the voltmeter and ammeter readings. Note the brightness of the bulb.
V2 ……………………………………………………………….. (½ mark)
A1………………………………………………………………….. (½ mark)

PROCEDURE 2
• Connect the circuit as shown in figure below

SET UP TWO
V3 ………………………………………………………………….. (½ mark)
• Put on the switch. Take note of the brightness of the bulb
V4 ………………………………………………………………………….. (½ mark)
A2………………………………………………………………………….. (½ mark)
5. Compare the values of V1 and V3 (1 mark)
6. Make a conclusion on (e) above (1 mark)
7. In which set up does the bulb light for a longer time? Explain in terms of A1 and A2 (1mark)

CONFIDENTIAL

Question 1:

1. A rectangular glass block of dimension; 10.0 cm (tolerance + or -0.2cm)
2. Four optical pins
3. Four paper pins or thumb pins
4. Protractor
5. Half metre rule

Question 2:

1.  A glass beaker.
2. A metal solid (100g mass labelled S)
3. Some water.
4. Source of heat.
5. A piece of cotton thread.
6. A plastic beaker wrapped with tissue paper on the outside.
7. A thermometer.
8. Liquid L. (distilled water)
9. Measuring instrument for mass (to be shared)
10. A Nichrome wire SWG 38(diameter range 0.36-0.38mm)
11. A 20g mass
12. A metre rule
13. A test –tube
14. A retort stand, boss and clamp
15. Two cells and two cell holders
16. A 2.5 V torch bulb in a bulb holder
17. 10 Connecting wires
18. A Switch
19. Ammeter (0 –2.5A),
20. Voltmeter (0 – 5 V)

CORRIGENDUM

QUESTION ONE:

• Soft board

QUESTION 2:

• A Nichrome wire SWG 28(dimeter range 0.36-0.38mm)
•  Two cell holders (able to hold a single cell)
• Ammeter (0 – 3 A),

MARKING SCHEME

QUESTION ONE

PART A

b) b = 6.2cm
g)P0Pi = 2.7 × 10−2 m   (1 mark) Reading and working in metres
h)Determine the ratio;       b       = n     6.2      = 62
b − P0Pi                6.2−2.7     35
n = 1.7714857

PART B

a)

g)

 i° 35 45 55 65 75 r° 24 29 31 33 36 d(cm) 1.4 1.9 3 4.3 5 e° 36 41 53 62 72

h)

i)

j) (i) r° = 40°
(ii) k sin r° = 1
k sin 40 = 1
k =     1
sin 40
= 1.5557

QUESTION  2

PART A

(a) Boiling point of water = 373 Kelvin (1 mark)

(b) Find the following measurements using appropriate instruments
Mass of the metal solid Ms= 100 g (1/2 mark)
Mass of the wrapped empty plastic beaker
M1 = 31.4g (1 mark)
Use the plastic beaker to measure 240m1 of liquid L, ence find the joint mass of the plastic beaker and its          content liquid L,
M2 = 276.1g
Initial temperature of liquid L, T, = 297 Kelvin (I mark)
(c) At boiling point of water, quickly transfer the metal solid into liquid L, stir well and measure the temperature of the mixture i ediately.
Temperature of the mixture
T2 = 304 Kelvin ( I mark)

(d) By using the measurements taken in parts (a), (b) and (c) as well as the equation provided below, determine the specific heat capacity of liquid L.
(Take S.H.0 of metal solid = 480Jkg-1k−1 and S.H.0 of plastic = 359 Jkg-1−1(1)
(Heat lost by metal solid) = (heat gained by liquid L) + (heat gained by plastic beaker)    (3 marks)

MsCsΔθs = MLCLΔθL + MpCpΔθ

100 × 480Jkg-1k−1 × (100 − 31) = 244.7kg × CL × (31− 24)
1000                                                   1000
+  31.4kg × 359 Jkg-1−1 × (31 − 24)
1000

33.2 = 1.7129CL + 7.89082
1.729CL = 3312 − 78.9082
CL = 3233.0918
1.729
= 1869.92Jkg-1k−1

PART B
a)Measure the length, L, of the nic ome wire provided
L = 50.0 cm

b) β = 0.5cm

d) N = 7 turns

e) h1 = 15.0cm

f) h2 = 200cm

g) Determine the spring constant K in S.I units. (1 mark)
F = Ke
K = F/E = mg/e = 20 × 10‾³ × 10N/kg
(20−15) × 10−2m
= 4 N/m
h) Obtain the constant, p, for the wire from the expression: (211i-an
P = 4mgR³
Kr4
= 4 × 20 × 10‾³ × 10 × 1.4691842 × 10−6
4 × 1.6702 × 10−16
= 1.75929 × 109

Where: m is the mass used, g is acceleration due to gravity ( g = 10m/s2 ),
R =   L     and r =   β
2πN               2πN
R = 50 × 10‾²                     r = 0.5 × 10‾²
2π7                                      2π7
= 0.0113682                      = 0.0001136821
R³ = 1.4691482 × 106            r4 = 1.6702 × 10−16

PART C

Procedure I

V1 = 3.1V
b) Read and record the voltmeter and ammeter re ings. Note the brightness of the bulb.
V2 = 2.8V
A1 = 0.20A

Procedure 2

V3 = 1.5V
• Put on the switch. Take note of the brightness of the bulb
V4 = 1.4V
A2 = 0.10A
e) Compare the values of V1 and V3
V3 is half of V
f) Make a conclusion on (e) above
The e.m.f of the two cells in series is 3.0V while the e.m.f of two cells in parallel is 1.5V
g) In which set up does the bulb light for a longer time? Explain in terms of A1 and A2 (1 mark)
In set up two only 0.1A is drawn buy the bulb while in set up one 0.20A is drawn by the bulb.

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