Instructions
- This paper consists of two questions 1 and 2.
- Answer ALL the questions
- Mathematical tables and electronic calculator may be used.
- Candidates should answer the questions in English.
QUESTIONS
QUESTION 1
You are provided with the following apparatus
- Two dry cells
- Nichrome wire mounted on the meter rule
- An ammeter
- Cell holder
- Voltmeter
- 8 connecting wires
- Switch
- A jockey
- Proceed as follows.
- Determine the electromotive force of the dry cells.
E =…………………………………….. (1 mark) - Draw a diagram to show how the e.m.f,E of the dry cells is measured. ( 1 mark)
connect the circuit as shown below - Connect the ends of A and C where AC is 100 cm across the terminals as shown above. Close the switch and record both ammeter reading and the voltmeter reading.
Current I = …………………………… ( 1 mark)
P.d (V) =………………………………. ( 1 mark) - Proceed for the lengths shown in the table and record the corresponding values of current,I and voltage,V ( 6marks)
Length L(cm)
100
70
60
50
40
20
I(A)
p.d(v) - Plot a graph of p.d,V(V) against current,I(A) (5 marks)
- Determine the slope of the graph. (3 marks)
- Given that E = V+Ir, determine the following using the graph above.
- Internal resistance r (1mk)
- The e.m.f E of the dry cells (1mk)
- Determine the electromotive force of the dry cells.
Question 2
PART A
You are provided with the following:
- A metre rule
- A knife edge
- One 50g mass and a 100 g mass
- Two pieces of threads each 30 cm long
- Some water in a beaker
- Liquid L in a beaker
- Tissue paper
Procced as follows- Balance the metre rule on the knife edge and record the reading at this point
Balance point =……………………………………cm mark (1 mark)
For the rest of this experiment the knife edge must be maintained at this position. - Set up the apparatus as shown in the figure below
The balance is obtained by adjusting the position of 100g mass when 50 g mass is fully immersed in water. Record the values of X and D.
X=…………………………………………………… ( 1 mark)
D=…………………………………………………… ( 1 mark) - Using the principle of moments;
- determine the weight W1of the 50g mass in water (2 marks)
- determine the Upthrust UW in water (1 mark)
- Remove the 50 g mass from the water and dry it using a tissue paper.
Keeping D constant, adjust the position of 100g mass until the metre rule is balanced and record the value of distance X.
X =…………………………………………………….. (1 mark)- Determine the weight W2 of the 50g mass in liquid L. ( 2 marks)
- Determine the Uphtrust UL in the liquid. ( 1 mark)
- Determine the relative density R.D of the liquid L, given that
R.D=UL/UW (2marks) - Find the density of liquid X in S.I unit (2marks)
- Balance the metre rule on the knife edge and record the reading at this point
PART B
You are provided with the following:
- A semi-circular glass block
- Soft board
- White paper
- Four Optical pins
- Two Thumb pins
- Vernier calipers
Procedure- Measure the thickness of the glass block using the Vernier calipers provided
t = ________cm __________m (1mk) - Fix the plain paper to the soft board using drawing/thumb pins
- Place the semi-circular glass block on the paper and trace its outline. Remove the block and label A and B as shown in figure above.
- Identify the centre O of the plane and draw the normal at that point as shown in the figure above.
- Measure incident angle i as 480 then draw the incident ray
- Place two pins P1 and P2 on the incident ray as shown.
- Move your eyes at curved face and locate the images of pins P1 and P2, place pins P3 and P4 such that the four pins are aligned in a straight line.
- Remove the glass block and join points P3 and P4 to meet the interface AB.
- Measure the angle Y between incident ray and the reflected ray.
Y= ___________ (2 marks)- Find the value of M given that (3marks)
M = (tY/2)-1 - Hand in the white paper used (1mark)
- Find the value of M given that (3marks)
- Measure the thickness of the glass block using the Vernier calipers provided
CONFIDENTIAL
Question 1:
- Two dry cells and a cell holder
- An ammeter
- A voltmeter
- Metre rule mounted with a nichrome wire( 28 gauge)
- A switch
- 8 connecting wires
Question 2
- Metre rule
- A knife edge
- 50g mass and a 100g mass
- Two pieces of threads each 30 cm long
- 100 ml of Water in a beaker
- 100 ml of glycerine(Liquid L) in a beaker
- Tissue paper
- 4 optical Pins
- semi-circular glass block
- two thumb pins
- soft board
- plain papers
- Vernier calipers
MARKING SCHEME
QUESTION 1
You are provided with the following apparatus
- Two dry cells
- Nichrome wire mounted on the meter rule
- An ammeter
- Cell holder
- Voltmeter
- 8 connecting wires
- Switch
- A jockey
- Proceed as follows.
- Determine the electromotive force of the dry cells.
E =……3.0V±0.1…….. (1 mark) - Draw a diagram to show how the e.m.f,E of the dry cells is measured. ( 1 mark)
- Connect the ends of A and C where AC is 100 cm across the terminals as shown above. Close the switch and record both ammeter reading and the voltmeter reading.
Current I = …0.12A±0.05…… ( 1 mark)
P.d (V) =……2.60V±0.10…………. ( 1 mark) - Proceed for the lengths shown in the table and record the corresponding values of current,I and voltage,V ( 6marks)
Length L(cm)
100
70
60
50
40
20
I(A)
0.12 0.16 0.18 0.20 0.24 0.36 p.d(V) 2.60 2.45 2.40 2.20 2.10 1.75 - Plot a graph of p.d,V(V) against current,I(A) (5 marks)
- Determine the slope of the graph. (3 marks)
slope= ΔV(v)
ΔI(A)
=3.0-2.2
0-0.225
slope =0.8
0.225
= -3.5556 ohms - Given that E = V+Ir, determine the following using the graph above.
- Internal resistance r (1mk)
v=-vI+E
y=mx+c
m=v
v=3.555ohms - The e.m.f E of the dry cells (1mk)
emf, E=3.0
- Internal resistance r (1mk)
- Determine the electromotive force of the dry cells.
Question 2
PART A
You are provided with the following:
- A metre rule
- A knife edge
- One 50g mass and a 100 g mass
- Two pieces of threads each 30 cm long
- Some water in a beaker
- Liquid L in a beaker
- Tissue paper
Procced as follows- Balance the metre rule on the knife edge and record the reading at this point
Balance point =……50.0±0.5………cm mark (1 mark)
For the rest of this experiment the knife edge must be maintained at this position. - Set up the apparatus as shown in the figure below
The balance is obtained by adjusting the position of 100g mass when 50 g mass is fully immersed in water. Record the values of X and D.
X=………17.5±0.5cm……………… ( 1 mark)
D=………39.8±0.5 cm…………………… ( 1 mark) - Using the principle of moments;
- determine the weight W1of the 50g mass in water (2 marks)
F1d1=F2d2
w1 ×39.8
100
=0.1×17.5
100
w1=0.0175
0.398
w1=0.04396N - determine the Upthrust UW in water (1 mark)
Uw=wA-w1
=0.5-0.04396
=0.456N
- determine the weight W1of the 50g mass in water (2 marks)
- Remove the 50 g mass from the water and dry it using a tissue paper.
Keeping D constant, adjust the position of 100g mass until the metre rule is balanced and record the value of distance X.
X =…17.0±0.5 cm………….. (1 mark)- Determine the weight W2 of the 50g mass in liquid L. ( 2 marks)
f1d1=f2d2
w2 × 39.8 = 0.1×17.0
100 100
w2=0.04271N - Determine the Uphtrust UL in the liquid. ( 1 mark)
uL=w4-wL
=0.5-0.04271
=0.45729N
- Determine the weight W2 of the 50g mass in liquid L. ( 2 marks)
- Determine the relative density R.D of the liquid L, given that
R.D=UL/UW (2marks)
R.D =0.45729
0.456
=1.002829 - Find the density of liquid X in S.I unit (2marks)
- Balance the metre rule on the knife edge and record the reading at this point
PART B
You are provided with the following:
- A semi-circular glass block
- Soft board
- White paper
- Four Optical pins
- Two Thumb pins
- Vernier calipers
Procedure- Measure the thickness of the glass block using the Vernier calipers provided
t = ___1.50_____cm ___0.015_______m (1mk) - Fix the plain paper to the soft board using drawing/thumb pins
- Place the semi-circular glass block on the paper and trace its outline. Remove the block and label A and B as shown in figure above.
- Identify the centre O of the plane and draw the normal at that point as shown in the figure above.
- Measure incident angle i as 480 then draw the incident ray
- Place two pins P1 and P2 on the incident ray as shown.
- Move your eyes at curved face and locate the images of pins P1 and P2, place pins P3 and P4 such that the four pins are aligned in a straight line.
- Remove the glass block and join points P3 and P4 to meet the interface AB.
- Measure the angle Y between incident ray and the reflected ray.
Y= ___96°±2°________ (2 marks)- Find the value of M given that (3marks)
M = (tY/2)-1
m=(0.015×96)-1
2
=1.388
=1.4 - Hand in the white paper used (1mark)
- Find the value of M given that (3marks)
- Measure the thickness of the glass block using the Vernier calipers provided
Download Physics Paper 3 Questions and Answers with confidential - Kenya High Post Mock 2023 Exams.
Tap Here to Download for 50/-
Get on WhatsApp for 50/-
Why download?
- ✔ To read offline at any time.
- ✔ To Print at your convenience
- ✔ Share Easily with Friends / Students