P2 Revision Questions

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1 P2 Revision Questions Part 1

2 Question 1 What is an alternating current?

3 Answer 1 Where electrons move backwards and forwards across a point (not in one direction)

4 Question 2 What is a direct current?

5 Answer 2 Where electrons flow in one direction

6 Question 3 What produces an alternating current and what produces a direct current?

7 Answer 3 Photocells and batteries make DC. Dynamos and generators make AC

8 Question 4 What is a photocell?

9 Answer 4 A device that converts light into electricity

10 Question 5 What material do photocells contain?

11 Answer 5 Phosphorus

12 Question 6 How do photocells work?

13 Answer 6 Light (photons) knock electrons free from atoms, creating a current

14 Question 7 What does renewable and non-renewable mean?

15 Answer 7 Renewable: Energy that can be replenished at a fast rate. Non-renewable: Energy that is used up faster than it is being replaced

16 Question 8 What is a fossil fuel? Give 3 examples

17 Answer 8 A fuel made from dead plants/ animals. Coal, gas and oil

18 Question 9 Name 3 different renewable energy resources

19 Answer 9 Wind, solar, nuclear

20 Question 10 What is passive solar heating?

21 Answer 10 Radiation comes in through large windows, heats objects and floors, radiation is emitted from these at night to heat the room (less wavelength and is now trapped)

22 Question 11 What are 3 advantages and 3 disadvantages of wind power?

23 Answer 11 Advantages: Renewable (made by Sun) no greenhouse gases, used in remote places. Disadvantages: Noisy, visual impact, wind farms take up a lot of room

24 Question 12 What are 3 advantages and a disadvantage of solar power?

25 Answer 12 Advantages: Robust, can work for a long time, renewable/ no greenhouse gases. Disadvantages: Less electricity produced when its dark/ cloudy,

26 Question 13 What is a generator? What is it made from?

27 Answer 13 Something that generates AC. It is a magnet spinning in a coil or vice-versa

28 Question 14 What 3 things can you change to increase the size of the current made by a generator?

29 Answer 14 Spin it faster, increase number of coils and increase strength/ size of magnet (or use electromagnet)

30 Question 15 What happens if you move a magnet into a coil of wire?

31 Answer 15 It produces (induces) an alternating current

32 Question 16 What does an alternating current look like on a graph?

33 Answer 16

34 Question 17 What are the two different types of transformer?

35 Answer 17 Step-up and step-down

36 Question 18 What does a step-up transformer do to the current and the voltage?

37 Answer 18 Increases voltage and decreases current

38 Question 19 What does a step-down transformer do to the current and the voltage?

39 Answer 19 Decreases voltage and increases current

40 Question 20 What is the national grid?

41 Answer 20 Series of pylons and transformers used to transmit electricity across the country

42 Question 21 What is the conservation of energy?

43 Answer 21 Energy cannot be created or destroyed, just transferred from one form to another

44 Question 22 What is meant by efficiency?

45 Answer 22 What percentage of input energy is transferred to useful energy

46 Question 23 How does a power station work. 1. Fuel is burnt.

47 Answer Water is boiled to make steam 3. Steam turns turbines 4. Turbines turn generators to make an AC

48 Question 24 What is most energy lost as?

49 Answer 24 Heat (and sound)

50 Question 25 What is the greenhouse effect?

51 Answer 25 Where infrared radiation is trapped in the atmosphere by greenhouse gases causing an increase in temperature

52 Question 26 What is global warming?

53 Answer 26 The apparent increase in the Earth s average surface temperature

54 Question 27 What are the three main greenhouse gases?

55 Answer 27 Carbon dioxide, water vapour and methane

56 Question 28 Explain how greenhouse gases cause the greenhouse effect

57 Answer 28 Absorb IR radiation and emits it with lower frequency, trapping it in the atmosphere

58 Question 29 Name a cause of each main greenhouse gas

59 Answer 29 Cars = carbon dioxide Methane = cows/ swamps Water vapour = Respiration/ plants

60 Question 30 How do volcanoes, deforestation and photosynthesis affect the levels of carbon dioxide in the atmosphere?

61 Answer 30 Volcanoes = increase Deforestation = increase Photosynthesis = Decrease

62 Question 31 What are these measured in: a) power b) energy c) time

63 Answer 31 Watts Joules Seconds

64 Question 32 What is a kilowatt hour (a unit) and why do we use it?

65 Answer 32 The amount of energy used by a 1 kilowatt appliance in an hour. Easier to deal with large energy numbers

66 Question 33 What are these measured in when we calculate the cost of energy: a) power b) energy c) time

67 Answer 33 Kilowatt, Kilowatt-hour, hour

68 Question 34 What does the cost of electricity depend on?

69 Answer 34 Power of appliance, how long it is used for, cost of electricity

70 Question 35 What is meant by off peak electricity? Why is this good?

71 Answer 35 Electricity used at times of low demand (night). It is cheaper than at peak times

72 Question 36 What transformer comes after a power station? What does this do to the voltage and current?

73 Answer 36 Step up- increases voltage and decreases current

74 Question 37 Why do we need to transmit electricity at high voltage around the country?

75 Answer 37 Low current- to reduce the amount of energy lost as heat- this also saves money

76 Question 38 What is biomass? Give 3 examples

77 Answer 38 Waste wood and other natural substances burnt in power stations

78 Question 39 What is ionisation? How can this affect the body?

79 Answer 39 Where radiation forms ions (making atoms charged). This can damage DNA to cause cancer

80 Question 40 What are the three different types of radiation?

81 Answer 40 Alpha Beta Gamma

82 Question 41 What can stop each type of radiation?

83 Answer 41 Alpha= paper/skin Beta = aluminium Gamma = lead/concrete

84 Question 42 Give 2 reasons why we use nuclear power

85 Answer 42 No greenhouse gases made, fossil fuels running out

86 Question 43 What do we have to do to dispose of the radioactive waste?

87 Answer 43 Seal it underground in shielded barrels, away from water supply, must be secure- you can t make a bomb but you can use it to contaminate water

88 Question 44 What is background radiation?

89 Answer 44 Background naturally emitted by the background (rocks)

90 Question 45 Which radiation can be used in smoke alarms? How does it work?

91 Answer 45 Alpha- ionises oxygen and nitrogen in air to make current- when there is smoke this stops and alarm goes off

92 Question 46 Which radiation can be used in testing paper thickness? How does it work?

93 Answer 46 Beta- If paper is thick less radiation let through, rollers press together. If too thin, more radiation is let through, rollers widened

94 Question 47 Which radiation can be used in tracers? How does it work?

95 Answer 47 Gamma- When atoms decay they give out gamma- we can detect where the gamma comes from

96 Question 48 What precautions do people take when handling radioactive waste?

97 Answer 48 Keep distance, protective clothing, use tongs, use shielding, store in shielded place

98 Question 49 What is the correct order of the 8 planets orbiting the Sun?

99 Answer 49 Mercury, Venus, Earth, Mars (asteroid belt) Jupiter, Saturn, Uranus, Neptune

100 Question 50 What keeps the planets orbiting the Sun?

101 Answer 50 Gravity (a centripetal force)