## Thursday, 4 September 2014

### 100 Physics revision questions for IGCSE and for O level

Physics revision questions (IGCSE and O LEVEL)

These short questions should help you prepare for the examination. Take g = 10 N/kg.

1   Write down the units for the following quantities:
mass   velocity   acceleration   temperature   density   pressure   energy   power   charge heat energy  current force   weight   momentum   work   wavelength  frequency  impulse specific latent heat   specific heat capacity

2   What is meant by:
specific heat capacity  specific latent heat  absolute zero  wavelength  impulse  moment of a force  efficiency  terminal velocity  mass number  half life  electrode  ecliptic

3   What is the formula for:
pressure   Ohm’s law   mechanical advantage   pressure in a liquid   acceleration power                 density  Boyle’s Law   specific heat  work done   wave velocity   electrical power

4 What instrument would you use to measure:
current   voltage   temperature  atmospheric pressure   liquid density

5 Explain the difference between the arrangement of molecules in a solid, liquid and a gas.

6   What happens to the molecules in a gas when it is:
(a) heated;
(b) compressed at a steady temperature?

7 An object moves 36 m in 4 s, what is its velocity?

8 An object accelerates from 3 m/s to 18 m/s in 10 s. What is its
(a)  average velocity;
(b)  acceleration;
(c)  final velocity;
(d)  distance travelled?

9 An object is dropped from rest:
(a)  how far does it fall in the first 5 s.
(b) What is its velocity at the end of that time?

10 Write down EIGHT points that should  be remembered when plotting a graph.

11 A force of 4 N acts on a mass of 2 kg. What is its acceleration?

12 If two equal and opposite forces act on an object. What happens to the motion of the object?

13 A force of40 N acts on a 4 kg mass for 3 s.
What is its:
(a) impulse;
(b) momentum change;
(c) acceleration?

14 A machine lifts a 24 kg mass a height of 5 m in 4 s. What is:
(a) the work done;       (b)           the energy gained;    (c) the power of the machine in watts?

15 A force of 4 N acts 4 m from the pivot of a lever.
(a) what force 8 in from the other side is needed to balance the lever?
(b) What is the moment of the force?

16 A force of 5 N stretches a spring by 4 cm. How far will a force of 15 N stretch the same spring?

17 What is the density of a solid if 5 kg of it have a volume of 200 cm3?

18 What two forces act on a floating object?

19 How does the density of a liquid affect how deeply a hydrometer will float in it?

20 How does the volume of a gas change when its pressure is increased?

21 Write down three uses of the expansion of solids.

22 What is a bimetallic strip and what is it used for?

23 What are the temperature ranges where you would use:
(a) a mercury in glass thermometer;
(b) an alcohol in glass thermometer?

24 If it takes 4200 J to heat 1 kg of water by 10C, how much heat energy is needed to heat 3 kg of water by 50C?

25 List in order of increasing conductivity of heat:
iron  copper  glass  wood   air

26 Which surfaces reflect heat best, black ones or shiny ones?

27 Which surfaces radiate heat best, black ones or shiny ones?

28 Which surfaces absorb heat best, black ones or shiny ones?

29 What temperature changes occur when water freezes?

30 What volume changes occur when water freezes?

31 Why is it difficult to make snowballs on a very cold day?

32 What is the effect of adding salt to boiling water?

33 What is the effect of adding salt to melting ice?

34 Calculate the heat needed to melt 5 kg of ice. (Specific latent heat of ice 340 000 J/kg.)

35  Calculate the heat given out when 3 kg of steam condense.
(Specific latent heat of steam = 2 250 000 J/kg.)

36  Write down the four strokes in the internal combustion engine and say briefly what happens during each stroke.

37  What is meant by the frequency and amplitude of a wave?

38  If the frequency of a sound signal is 660 Hz and its wavelength is 0.5 m, what is the velocity of sound?

39  Sketch how echoes may be used to find the depth of the sea.

40  How does an eclipse of the Sun occur?
How does an eclipse of the Moon occur?

41  Draw sketches to show the following:
(a) light reflected at an angle from a plane mirror;
(b) light reflected from a convex mirror;
(c) light reflected from a concave mirror;
(d) light refracted at a plane surface;
(e)  light passing through a concave lens;
(f)  light passing through a convex lens;
(g) light hitting a glass/air boundary at greater than the critical angle;
(h) white light passing through a prism.

42 Sketch ray diagrams for:
(a) a magnifying glass; (b) a telescope.

43  What three colours are needed to make white light?

44  Write down the following in order of increasing wavelength:

45  Draw two bulbs:
(a) in a series circuit;
(b) in a parallel circuit.

46  Which has the greater resistance a metre of thick wire or a metre of thin wire of the same material?

47  What happens to the resistance of a piece of wire if its temperature is raised?

48  What is a thermistor?

49  What are the restrictions to Ohm’s Law?

50  What is the colour code for the wires in a 13 A plug?

51  What is the purpose of a fuse?

52  What is the voltage of the mains in a house?

53  Draw a diagram to show how a 13 A socket would be connected in a house.

54  What are the anode, cathode and electrolyte in:
(a) a simple cell; (b) a lead accumulator.

55  How does a secondary cell differ from a primary cell?

56  Write down two other ways of producing electricity apart from a cell.

57  In a moving coil meter what prevents the pointer from going right off the scale for very small currents?

58  What is the resistance of a piece of wire that passes a current of 2 A when a voltage of 12 V is applied to it?

59  What is the power of a 12V  3A bulb?

60  At 8p per kWh how much does it cost to run a 250 W light bulb for 4 hours?

61  What do two north poles do to each other?

62  Write down two ways of magnetising an iron bar.

63  How are the magnetic properties of iron and steel different?

64  Draw the magnetic fields produced by a current in:
(a) a straight wire;
(b) a short coil;
(c) a long coil or solenoid.

65  Write down three ways of increasing the strength of an electromagnet.

66  In the d.c. motor what is the purpose of:
(a) the brushes; (b) the commutator?

67  What is needed to produce electricity by electromagnetic induction?

68  In a transformer, what is the core made of and why?

69  What is the difference between a step-up and a step-down transformer?

70  The primary of a transformer has 1200 turns and the secondary 400 turns. If the input voltage is 3000 V, what is the output voltage?

71  Will a transformer work using direct current, alternating current or both?

72  In the copper plating experiment, which electrode was copper plated.

73  If 2 g of copper were deposited by a current of 1.5 A flowing for 10 minutes, how much would be deposited by a current of 3 A flowing for 20 minutes?

74  Sketch the waveform produced by a simple d.c. generator.

75  What do two unlike charges do to each other?

76  What is thermionic emission?

77  What carries electric current in wires?

78  What is an ION?

79  Give three conditions necessary for a diode to work.

80  Is the anode the positive or negative electrode?

81  What is the effect on an electron beam of:
(a) a magnetic field; (b) an electric field.

82  What is a cathode ray?

83  Write down three properties of cathode rays.

84  Describe the scanning effect of a TV tube.

85  What are the colours of the three types of phosphor dots in a colour TV?

86  How does the brightness control affect the number of electrons in the bean, of a CR0?

87  Draw sketches to show the CR0 screen for the following inputs:
(a) time base off, d.c. input, top plate positive;
(b) time base on, d.c. input, top plate negative;
(c)  time base on, a.c. input;
(d) time base on, a.c. input in series with a diode.

88  Name the three parts of a transistor.

89  Which is larger, the base current or the collector current?

90 How can X-rays be produced?

91  Draw a carbon atom labelling
(a) electrons; (b) protons; (c) neutrons; (d) nucleus.

92  What is the charge on each of the above parts of the carbon atom?

93  What is the charge on the carbon atom as a whole?

94  What is meant by the isotope of an element?

95  Give three examples of the uses of radioactive isotopes.

96  What are the properties and nature of:
(a)  alpha particles;
(b) beta particles;
(c) gamma rays.

97  How does a Geiger counter work?

98  What would you use a cloud chamber for that you could not use a Geiger counter for?

99  An element has a half-life of 2500 years. If there was 10 g of radioactive atoms at the start, how much would be left after 10 000 years?

100      Explain with diagrams and equations what is meant by:
(a) nuclear fission;
(b) nuclear fusion;