PHYSICS FORM FOUR PAPER - Half-Yearly Examination 2006/2007.
PHYSICS FORM FOUR PAPER
M. A. Vassalli Junior Lyceum
Half-Yearly Examination 2006/2007
Form 4 Physics Time: 1hr 30mins
Name: _____________________ Class: _____________________ Mark:
Useful equations: H = m c ∆θ P t = m c ∆θ E = P t
SECTION A: This section carries 50 marks. Attempt all questions. Answer all the questions in
the space provided.
1. a. Heat energy travels through the bottom of a pan by ____________________. (1)
b. All metals are good ____________, while plastics, wood and air are good ________________ (2)
c. Heat energy can travel through empty space by __________________. (1)
d. Dull black surfaces are ___________ heat radiators and ______________ heat absorbers while
shiny bright surfaces are ____________ heat radiators and _____________ heat absorbers. (4)
2 The diagram shows the construction of a bridge. This bridge is made of steel to make it heavy-duty
and rustproof.
a. During hot sunny days the bridge _______________,
while during cold rainy days it ______________. (2)
b. What was the purpose of putting rollers at one end of
the bridge? (1)
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3. A Piece of Perspex is rubbed on wool and an electrostatic charge was built on the Perspex.
a. Does the Perspex obtain a positive or a negative charge? (1)
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b. Explain in terms of electrons how the charge was built up on the Perspex (2)
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c. If the Perspex is put close to small pieces of paper as shown,
describe how this would effects the charges in the paper. (Label
and draw charges on the diagram to help you explain better) (3)
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4. John wants to find the specific heat capacity of a loaf of bread. Before starting his experiment, he
took the reading of the thermometer hung in his kitchen
which showed a temperature of 25ºC. He puts the loaf in an
oven that is power rated 800W for 3 minutes. Each loaf has a
mass of 0.2kg
a. What is the amount of energy supplied? (3)
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b. The temperature of the loaf after being heated was 45ºC.
Find the specific heat capacity. (3)
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Perspex
Paper
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5 The diagram shows the setup used in a physics laboratory to see convection currents. Potassium
permanganate crystals were dropped gently at the bottom of the beaker as shown.
a. What was the purpose of adding these crystals? (1)
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b. What would you expect to see during the experiment? (2)
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c. Draw arrows in the beaker showing the motion of the liquid and label as hot and cold. (4)
d. Explain in terms of density how convection takes place (4)
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6. Earth is warmed by the sun’s rays. Heat is trapped in the Earth’s atmosphere by the greenhouse
effect. The diagram shows how these rays reach our planet.
a. What are the rays responsible for the planet’s warmth called? (1)
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b. Explain the term ‘Greenhouse effect’ (4)
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7. This electrostatic spray gun is used to paint some appliances’ parts. The paint is given a positive
charge.
a. Why are the paint droplets all given the same charge? (1)
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b. What happens to the appliances’ parts as the spray
approaches them? (2)
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c. Give one advantage of using an electrostatic spray gun
instead of a normal spray gun? (2)
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8. The following spheres were put on an insulating stands and a charged strip was put close as shown
in figure 1.
a. Name a suitable material for the strip. (1)
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b. Draw the charges on figure 1. (2)
c. While the strip was kept close to the spheres, sphere B was moved away from sphere A. Draw the
charges on figure 2. (2)
d. What happens if sphere A is earthed? (1)
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SECTION B: This section carries 35 marks. Attempt all questions. Answer all the questions on
the foolscaps provided.
9. The diagram shows how fuel is being put in a metal tank. Fuel passes through the pipe, through the
tap and then in the tank. The system is equipped with safety measures.
a. Explain how charge can build up on the fuel as it passes through the pipe (assume the fuel gets
negatively charged). (2)
b. Explain how the electrical connectors are reducing the risk of an explosion. (2)
c. Explain why using a plastic tank instead of a metal one would increase the risk of charge build up(2)
Charge builds-up even on cars. In fact cars require safety precautions to prevent charging. (Assume
that the car gets positively charged)
d. Explain how the charge builds up on a car as it is moving. (2)
e. What a safety measure is taken to keep the car neutral? (2)
f. Explain how this safety measure works (2)
g. Charge builds up even on the driver as he is in the car. While rubbing with the seat, charges are
transferred to his shirt. Why can this be dangerous as he opens the fuel tank’s tap? (2)
h. Name 1 safety precautions a driver should do, when he fills the car with fuel (1)
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10. A scientist is required to find the specific heat capacity c of an unknown liquid. He set the
apparatus as shown in the diagram, and added 0.5kg of the liquid. The heater was connected to a
joulemeter.
a. A is a ______________________ (1)
B is a ______________________ (1)
C is a ______________________ (1)
He obtained the following results.
Temperature / ºC 18 24 30 36 42 48
Time t / minutes 0 1 2 3 4 5
b. Plot a graph of temperature (y-axis) against time (x-axis) on the graph paper provided. (7)
c. From your graph or otherwise find the room temperature (1)
d. What do you notice about your graph that shows that the plastic container is well-lagged? (2)
e. The joulemeter in the diagram supplied 63,000 J in order to heat 0.5 kg of liquid. Find the
change in temperature as the liquid is heated . (1)
f. Find the time in seconds during which the heater is switched on. (1)
g. Calculate the power of the heater (2)
h. Calculate the specific heat capacity, c, of the liquid. (3)
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Half yearly Examination 2005/2006 Form 4 Marking Scheme
Section A 50marks
Question Answer Mark
1a conduction 1
1b conductors, insulators 1 + 1
1c radiation 1
1d good, good, bad , bad 1 + 1 + 1 + 1
2a expands, contracts 1 + 1
2b To have room for expansion 1
3a positive charge 1
3b electrons move from Perspex to cloth 2
3c attract electrons to the surface of the paper (induction) 2 + 1 (diagram)
4a 144,000 J 2 + 1 (unit)
4b 36,000 J/kgºC 2 + 1 (unit)
5a To see the convection currents 1
5b Violet moves up and then down with convection currents. 2
5c correct drawing and labeling 2 (arrows)
2 (labeling)
5d hot water – less dense ,rises
cold water _ more dense, goes down 4
6a Infra Red Rays 1
6b short wavelength I.R. rays penetrate atmosphere, loose energy,
wavelength increases and cannot go out of the atmosphere again. 4
7a like charges repel 1
7b get charged by induction 2
7c less paint used / wasted
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Parts covered with paint from both sides 2
8a Polythene 1
8b protons (+) on sphere A, electrons (-) on sphere B 2
8c protons (+) on sphere A, electrons (-) on sphere B 2
8d electrons flow from earth to Sphere A 1
Section B 35 marks
Question Answer Mark
9a electrons transferred to fuel by rubbing 2
9b Extra electrons go back to earth to neutralize the fuel 2
9c insulators do not loose charge by earthen 2
9d rubbing of the air particles 2
9e strip (conductor) 2
9f electrons move from earth to car 2
9g charge is transferred by means of sparks 2
9h Earth himself (touch a conductor) 1
10a heater, stirrer, thermometer 1 + 1 + 1
10b Labeled axis 2
Title 1
Graph plotted correctly 4
10c 18ºC 1
10d time and temperature are increasing proportionally 2
10e 30ºC 1
10f 300 seconds 1
10g 21W 1 + 1 (unit)
10h 4200 J/kgºC 2 + 1 (unit)
