Free Marking Schemes Form 3 Physics Paper 3 Exams

Name___________________________________________ Index No.____________                            

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PHYSICS

PAPER 3

PRACTICAL 

2 ½ HOURS

JOINT EXAMINATION TERM 3

INSTRUCTIONS TO CANDIDATES

• Answer all questions in both sections in the spaces provided in the question paper.
• Read the whole paper carefully before commencing your work.
• Marks are given for a clear record of the observations actually made, their suitability and accuracy and their use of them.
• Mathematical tables and electronic calculators may be used.

FOR EXAMINER’S USE ONLY

Question	Maximum Score	Candidate’s Score
1.	20
2.	20
TOTAL	40

This paper consists of 7 printed pages. Learners should check to ensure that all pages are printed as indicated and that no questions are missing.

Question 1

You are provided with the following;

• Masses; 10g, 20g(2), 50g and 100g
• A helical spring with a pointer
• The metre rule or half-metre rule

Proceeds as follows;

1. a) Suspend the helical spring vertically, alongside the clamped half-metre rule as shown in Figure 1 below. Determine the length, L₀ of the spring before loading it.

L₀=________________________________(cm)                                                      (1mk)

1. i) Load the spring with a mass of 20g and determine the new reading on the metre rule (L).

1. ii) Record this in the table below.

iii) Calculate the extension, e= L-L₀ due to the mass of 20g and record the value in the table given below.

1. Repeat steps b(i-iii) for other masses and complete the table.             (8mks)

Mass (g)	0	20	30	40	50	60	70	80	90	100
Weight (N) (Force)
Reading L (cm)
Extension e (cm)

1. Plot a graph of Force(N) against extension e (cm).             (5mks)

• Determine the slope S of the graph.             (3mks)

1. Given that K=Se, determine the value of K where S is the slope of the graph and e is the extension of the spring when loaded with a 50g mass.             (3mks)

Question 2

You are provided with the following;

• A Nichrome wire mounted on a millimetre scale YZ.
• A carbon resistor R (10Ω)
• 8 connecting wires
• Ammeter
• Voltmeter
• 2 dry cells
• Cell holders
• Switch

2. (a) Set up the circuit as shown below.
3. Record the voltmeter reading when the switch is open.

E=_____________________________________                                         (1mk)

1. Close the switch and record the voltmeter and ammeter readings.

Voltmeter reading, V=_______________________________                     (1mk)

Ammeter reading, I=________________________________                      (1mk)

• Explain why V is less than E.             (2mk)

______________________________________________________________________________________________________________________________________________________________________________________________________

1. Now connect the voltmeter across the carbon resistor R and record the voltmeter reading V₁ when the switch is on.             (1mk)

V₁=

1. Determine R given that; R=             (3mks)

(b)

• Measure and record the diameter, d of the resistance wire (YZ) using a micrometre screw gauge.

d= ___________________________________mm

d=___________________________________m                                           (2mks)

1. ii) Set up the circuit as shown in the figure;

• Determine the current I flowing in the circuit.

I=__________________________________                                                 (1mk)

1. Now connect the voltmeter across wire (YZ) and record the p.d, V₂ across wire YZ.

V₂= ________________________________                                                 (1mk)

1. Determine the resistance R of the wire YZ.             (3mks)

1. Determine k, the resistance per metre of wire YZ. (2mks)

• Determine Q given that Q=(where d is in metres)                    (2mks)

________________________________________________________________________

JOINT EXAMINATION

FORM 3PP3 PHYSICS

TERM 3 MARKING SCHEME

1. a) L₀ – ½mk answer to 1d.p

½mk correct unit (cm)

1. ii) (8mks)

Mass (g)	0	20	30	40	50	60	70	80	90	100
Weight (force) N
Reading, L cm
Extension, e(cm)		1.0	2.6	4.8	6.3	8.1	10.2	12.3	14.2	16.4

2mks@ Row (force) – correct evaluation and substitution

F = mg

L to 1 d.p

e correct (L-L₀) to 1 d.p

1. v) Graph of Force(N) vs extension, e (cm). (5mks)

Correct labelling of axis – 1mk

Scale – simple and uniform – 1mk

Plotting (2mks) (7-10 points) – 2mks

(5-6 points) – 1mk

(0-4 points) – 0 mk

Line – straight line passing through the origin – 1mk

1. vi) Slope, s== 0.8N/cm                         (3mk)

Clear points from the graph – 1mk

Correct evaluation – 1mk

Answer – ½mk

Correct unit – ½mk

vii) Correct substitution of k=se – 1mk

Correct evaluation – 1mk

Answer – ½mk

Correct unit – ½mk

2. a)
3. E = 3.0- ½mk

Correct unit – ½mk

2. V = 2.5v1 1 d.p (1mk) and correct unit

I = 0.20A 0.02 2 d.p (1mk) and correct unit

• V is less than E due to the lost voltage; voltage against the internal resistance of the cell. (2mk)

1. V₁ = 1.4V1 Correct reading to 1 d.p – ½mk

Correct unit – ½mk

1. R=1

Correct substitution – ½mk

Correct evaluation – ½mk

Answer in 4s.f – ½mk

Correct unit – ½mk

b          (i)        d=0.36mm

d= in metres – correct conversion to 5 d.p  (1mk)

(iii)      I = 0.10A     Correct reading – ½mk

Correct unit – ½mk

iv)V₂ = 1.9v  0.1      Correct reading – ½mk

Correct unit – ½mk

1. v) R= Correct substitution – 1mk

Correct evaluation – 1mk

Answer in 4s.f – ½mk

Correct unit – ½mk

1. K=Correct evaluation – 1mk

Answer – ½mk 4s.f

Correct unit – ½mk (Ωm^-1)

• Q= Correct evaluation – 1mk

Answer in 4s.f – ½mk

Correct unit – ½mk  (Ωm)