## Physics Paper 3 Questions and Answers with Confidential - Form 3 Mid Term 2 Exams 2021

INSTRUCTIONS TO CANDIDATES

• Answer ALL the questions in the spaces provided in the question paper.
• You are supposed to spend the first 15 minutes of the 24 hours allowed for this paper reading the whole paper carefully before commencing your work.
• Marks are given for a clear record of the observations actually made, their suitability, accuracy and the use made of them.
• Candidates are advised to record their observations as soon as they are made.
• Non-programmable silent electronic calculators may be used.
• Candidates should answer the questions inEnglish.
For Examiner's Use Only

QUESTION ONE

You are provided with the following apparatus;

• Metre rule
• Small piece of plasticine
• 250ml beaker
• 3 pieces of cotton thread each 30cm long
• A piece of cellotape 5cm
• A measuring cylinder 100ml
• A stand and clamp
• 50g mass
1. Using 30cm thread, suspend the metre rule at the 50cm marks. You may use some plasticine to ensure that the balance is exactly at 50cm.
2. Suspend the empty beaker at 40cm mark and hang the 50g mass to the other side

Move the 50g mass until the metre rule balances horizontally. Record the distance
q = ______________cm      (1mrk)
Use the cello tape provided to fix the position of the 50g mass. Note the point of suspension must remain the same throughout the experiment.
3. Using the measuring cylinder measure 20cm3 of water and add it to the beaker. By varying the length Z obtain the new point and record it in the table below.
4. Repeat the procedure above for other values of volumes as shown in the table, hence complete it
 Volume V cm3 0 20 40 60 80 100 120 Length Z cm 1/z cm−1
(7mrks)
5. Plot a graph of volume V against 1/z      (5mrks)
6. Determine the slope S of the graph  (3mrks)
7. From the equation V = 1000(50q) – 1000m
dz         d
Determine the values of
1. D     (2mrks)
2. m     (2mrks)

QUESTION 2

You are provided with the following apparatus

• an ammeter
• a voltmeter
• Two dry cells
• a cell holder
• potentiometer/variable resistor
• connecting wires
1. Connect the apparatus as shown below
2. Adjust the potentiometer until you are able to obtain minimum reading on the voltmeter and maximum on the ammeter. Record these readings in the table below.
 V (V) I (A) v/l 1/l
(12mrks)
3. By adjusting the potentiometer, obtain five more readings at an interval of 0.5V and complete the table
1. Plot a graph or against  v/ against 1/ (5mrks)
2. The equation fo rthe graph by V/lE/l − k where E and k are constants. From the graph determine the value of E and k. (3mrks)

CONFIDENTIAL

CONFIDENTIAL INSTRUCTIONS TO SCHOOLS

• The information contained in this paper is to enable the head of school and teacher in charge of physics to make adequate preparations for this term’s physics practical examination. NO ONE ELSE should have access to this paper or acquire knowledge of its contents. Great care must be taken to ensure that the information herein does not reach the candidates either directly or indirectly.
• The physics teacher is NOT expected to perform the experiments
• The apparatus required by each student for the physics end of term’s practical examination are set out on the next page. It is expected that the ordinary apparatus of a physics laboratory will be available.
• The physics teacher should note that it is his/her responsibility to ensure that each apparatus acquired, for this examination agrees with specifications on the next page.
1. QUESTION ONE
• Metre rule
• Small piece of plasticine
• 250ml beaker
• 3 pieces of cotton thread each 30cm long
• A piece of cellotape 5cm
• A measuring cylinder 100ml
• A stand and clamp
• 50g mass
2. QUESTION TWO
• an ammeter
• a voltmeter
• Two dry cells
• a cell holder
• potentiometer/variable resistor (50Ω)
• connecting wires

## MARKING SCHEME

QUESTION ONE

1. Using 30cm thread, suspend the metre rule at the 50cm marks. You may use some plasticine to ensure that the balance is exactly at 50cm.
2. Suspend the empty beaker at 40cm mark and hang the 50g mass to the other side
Move the 50g mass until the metre rule balances horizontally. Record the distance
q =7cm use student’s value  cm (1mrk)
3. Repeat the procedure above for other values of volumes as shown in the table, hence complete it
 Volume V cm3 0 20 40 60 80 100 120 Length Z cm 10 7 5 4 3.5 3 2.5 1/z cm−1 0.1 0.14 0.2 0.25 0.29 0.33 0.4
(7mrks)
1⁄2 mrk for each
4. Plot a graph of volume V against 1 (5mrks)
• Graph is a straight line
5. Determine the slope S of the graph (3mrks)
Substitution 1mrk
Simplification 1mrk
Range 400±8 1mrk
6. From the equation V = 1000 (50q) − 1000m
dz          d
Determine the values of
1. d         (2mrks)
slope = 50q 400 = 50×7 d = 0.875 q is substituted, check student’s working
d                d
2. m          (2mrks)
y- Intercept = 100m
d
Extrapolation 1mrk
Substitution 1mrk

QUESTION 2

1. Connect the apparatus as shown below
2. Adjust the potentiometer until you are able to obtain minimum reading on the voltmeter and maximum on the ammeter. Record these readings in the table below.
 V (V) 0.2 0.6 1.1 1.6 1.8 2.1 (increasing trend) I (A) 0.18 0.12 0.10 0.08 0.06 0.04 (decreasing trend) v/l Student's working 1/l Student's working
(12mrks)
3. By adjusting the potentiometer, obtain five more readings at an interval of 0.5V and complete the table
4. Plot a graph or against  v/ against 1/ (5mrks)
Graph is a straight line with a negative y- intercept
Axes labeled 1mrk
Scale simple and uniform 1mrk
Plotting 6pts 2mrks, 3 – 4pts 1mrk
Straight line 1mrk
5. The equation fo rthe graph by V/l = E/l − k where E and k are constants. From the graph determine the value of E and k. (3mrks)
Slope of graph gives E = 2.99V (slope 1mrk)
K = y- intercept (positive value negative cancels)
Values of K and E 1mrk each

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