# Physics Paper 3 Questions and Answers - Alliance Mock Examinations 2022

QUESTIONS

Question 1
Apparatus

• Two retort stands
• Two pieces of strings(about 70cm long)
• Cello tape
• Half-meter rule
• Stop watch
• Meter rule

Proceed as follows:

1. Set the apparatus as shown in the figurel, with the suspending length L of the threads being 60 cm and the points of suspension of the threads on the rule at 5 cm from either end. The threads should be fixed firmly at the knots using cello tape, so that the rule rests on a horizontal plane.
2. Displace the two ends of the rule through a small angle along the horizontal, so that the rule performs oscillations along the horizontal plane. Determine and record the time t for 10 oscillations.
3. Adjust the suspending lengths L of the threads to L= 55.0cm, and repeat step (ii) above.
4. Repeat step (iii) for the other values of L and complete the table 1 of results.
1. Table 1
 L (cm) x 102 Time for 10 oscillations t (s) Periodic time T(s) Log L Log T x102 0.60 0.55 0.50 0.45 0.40 0.35 0.30
(6mks)
2. In the grid provided, Plot a graph of log Tx102 against log L
3. Determine the slope of the graph.
4. Given that Log T x 102 = log k + nlogL, Find the value of
1. n (1mk)
2. k
3. T when L 70cm

Question 2
PART A
You are provided with the following apparatus

• A triangular prism
• Four optical pins
• Soft board
• Plain sheet of paper
• Protractor
• A piece of masking tape

Proceed as follows

1. Attach the plain sheet of paper on a soft board using the masking tape. Place the triangular prism at the middle of the sheet of paper as shown.
2. Draw the outline of the prism. Remove the prism.
3. At a point about a third way along one side of the outline from angle A, draw a normal
4. Draw a line at angle I= 50° to the normal. Stick two pins p1 and p2 vertically on this line. Place the prism accurately on the outline. By viewing through the opposite side, stick two other pins P3 and P4 vertically such that they are in line with the two images of pins P1 and P2.
5. Remove the prism and the pins. Draw a line joining the marks made by P3 and P4. Extend the lines P1P2 and P3 and P4 to intersect. Hence measure the angle of deviation
D=...........(1mk)
6. For one other value of angle, i shown in the table below locate and measure the corresponding angle of deviation. Complete the table.2 (2mks)
Table 2
 i 50° 60° D
7.
1. Determine the average value Dm of D
2. Determine the constant K using the equation
K = SinA+Dm
2
sinA/2
PART B
You are provided with the following:
• A carbon resistor marked X
• Resistance wire marked R
• Micrometer screw gauge(to be shared)
• Voltmeter
• Ammeter
• Resistance wire mounted on a mm scale belled L
• A cell, cell-holder
• Centre-zero Galvanometer
• 8 connecting wires
• Jockey
Proceed as follows
8. Using the micrometer screw gauge, measure and record the diameter D of the resistance wire R provided
D..............m (1mk)
9. Set up the following circuit.
10.
1. Record the voltmeter reading when the switch is open.
E=.........V (1mk)
2. Close the switch and record the voltmeter and ammeter readings V and I
V=............V (1mk)
I.................A(1mk)
3. Account for the difference of E and V.(1mk)
11. Now connect the voltmeter across the carbon resistor X and record the voltmeter reading V1
V1...........V (lmk)
12. Calculate X given that
x= V1/(2mk)
Connect another circuit as shown below:

1. Move the sliding pointer along the resistance wire until the galvanometer reading comes to zero. Record L and L2
2. Obtain the value of the unknown resistance R given that,
Interchange the position of Rand X and repeat the procedure in (i) above and calculate the value of R.
X/R = L1/L21 let it be R2
13.
1. Complete the table below with the values L1, L2, R and R2 (4mks
Table 3
 Trial 1 L1 (cm) R1 L2 (cm) Trial2(after interchanging) L1 (cm) R2 L2 (cm)
2. Calculate the average value of R.
3. given that, R = 355/100πD2 determine the value of S. (2mks)

## MARKING SCHEME

1.

1. Table 1
 L (cm) x 102 Time for 10 oscillations t (s) Periodic time T(s) Log L Log T x102 0.60 15.00-16.00 '1.600' '1.7782' 20.41 0.55 14.00-15.00 1.7404 0.50 13.00-14.00 1.6990 0.45 12.00-13.00 1.6532 0.40 11.00-12.00 1.6021 0.35 10.00-11.00 1.5441 0.30 9.00-10.00 '1.050' 1.4771 '2.119'
2.
3. n = slope = ΔLogT = (20 - 2.0)
ΔLog L   1.8 - 1.5
= 0.60
4.
1. n = 0.60
1.
2.
3.
4.
5. D = 38º - 42º
6.
 i 50° 60° D 40º ± 2 42º ± 2
7.
1. '40' + '42' = 41º
2
2. sin 60 + '41' = sin'0.5' = 1.543
sin60/2       sin60/2
k = antilog of y-intercept
k = 10 = 1/10 = 0.10
0.090 ≤ n ≤ 1.5
T when L = 70cm
LogT = logK + nLogL
substitution
1.2555
± 0.2
OR
By interpolation antilog q-value
8. D - 0.0220 - 0.0320
9.
10.
1. E - 1.4 - 1.6
2. V = 1.3 - 1.5
I = 0.11 - 0.13
3. It is the ord across the cell which is not in use
In use, v, ord across the cell in use
11. v1 =  1.1 - 1.3V
12. x = v1/I = '1.2' / '0.12'
= 10R
13.
1.
 Trial 1 L1(cm) 51.0 - 61.0 R1 = XL1 = '23.33'           L L2(cm) 19.0 - 29.0 Trial 2 L1(cm) 21.0 - 31.0 R2 = '20.76' L2(cm) 19.0 - 9.0
2. '23.33' + '20.76' = '22.045'R
2
3. '22.045' =   358
100 x 11 x 0.027
S = 0.1443

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