G482 Revision Ques3ons

Transcription

1 G482 Revision Ques3ons Part 1

2 Ques3on 1 Explain what an electric current is

3 Answer 1 Rate of flow of charge

4 Ques3on 2 Define what a conven3onal current is

5 Answer 2 Describes the movement of charge of posi3ve par3cles from + to -

6 Ques3on 3 Describe what is meant by electron flow

7 Answer 3 The movement of electrons from to +

8 Ques3on 4 Define the Coulomb

9 Answer 4 Unit of charge = 1As

10 Ques3on 5 What is the difference between an electric current and an electrolyte?

11 Answer 5 Electric current is electrons moving. Electrolyte current is ions moving

12 Ques3on 6 How do you use an ammeter to measure the current of a circuit?

13 Answer 6 Place an ammeter in series anywhere in the circuit

14 Ques3on 7 What is the charge of an electron?

15 Answer 7 - e=- 1.6x10-19 C

16 Ques3on 8 Define Kirchoff s first law. What is this a conserva3on of?

17 Answer 8 The sum of the currents entering a junc3on is equal to the sum of the currents exi3ng the junc3on. Conserva3on of charge

18 Ques3on 9 State what is meant by mean dri] velocity of charge carriers

19 Answer 9 Average velocity of an electron as it travels through a wire due to a PD

20 Ques3on 10 What is the difference between conductors, insulators and semiconductors?

21 Answer 10 Conductors have a greater number density of electrons

22 Ques3on 11 Define Poten3al difference

23 Answer 11 The amount of energy per charge converted from electrical into another form

24 Ques3on 12 Define EMF

25 Answer 12 The amount of energy per charge converted from one form into electrical

26 Ques3on 13 Define the volt

27 Answer 13 JC - 1

28 Ques3on 14 Describe how you can use a voltmeter to measure the PD of a component

29 Answer 14 Place is around the component (parallel to it)

30 Ques3on 15 Define the Ohm

31 Answer 15 1VA - 1

32 Ques3on 16 State Ohm s law

33 Answer 16 Electric current through a conductor is propor3onal to the PD across it provided physical condi3ons are kept constant (temp)

34 Ques3on 17 Define resistance

35 Answer 17 A property that regulates the amount of current flowing through it R=V/i

36 Ques3on 18 What does the I- V graph look like for an Ohmic device

37 Answer 18

38 Ques3on 19 What does the I- V graph look like for a filament lamp

39 Answer 19

40 Ques3on 20 What does the I- V graph look like for an LED

41 Answer 20

42 Ques3on 21 Describe an experiment to determine the I- V graph of a component

43 Answer 21 Ammeter in circuit, voltmeter around component. Measure PD and current. Change resistance in circuit and repeat. Make graph of results

44 Ques3on 22 Describe an advantage of using LED s

45 Answer 22 Robust, low PD, long life, switch on instantly

46 Ques3on 23 Define the resis3vity of a material

47 Answer 23

48 Ques3on 24 What is the equa3on for resis3vity

49 Answer 24

50 Ques3on 25 Describe how the resis3vity's of metals and semiconductors are affected by temperature

51 Answer 25 Increase temperature it increases resis3vity

52 Ques3on 26 Describe what is meant by the displacement of a wave

53 Answer 26 The distance a point of the wave has from the rest point

54 Ques3on 27 How is the resistance of a wire affect by temperature

55 Answer 27 As you increase the temperature, the resistance decreases

56 Ques3on 28 How is the resistance of a NTC thermistor affected by temperature

57 Answer 28 As you increase the temperature, the resistance decreases

58 Ques3on 29 Describe what power is

59 Answer 29 Rate that electricity is transferred/ work is done

60 Ques3on 30 Explain how a fuse works

61 Answer 30 A piece of wire that melts and breaks a circuit when a high current causes it to heat up

62 Ques3on 31 How do you determine the correct fuse to use?

63 Answer 31 Choosing a current ra3ng that is slightly above the current that the wire will be carrying

64 Ques3on 32 Define what a kilowal- hour is

65 Answer 32 Energy used by a 1kW appliance in 1hour=3.6MJ

66 Ques3on 33 Describe the equa3on to calculate energy in kilowal- hours

67 Answer 33 Energy=Power x 3me Power is measured in kw 3me is measured in hours

68 Ques3on 34 Describe what Kirchoff s second law is. What is it a conserva3on of?

69 Answer 34 The sum of the EMF is equal to the sum of the PD s in a closed loop

70 Ques3on 35 How do you calculate the total resistance of resistors in series?

71 Answer 35 Add the resistances together

72 Ques3on 36 How do you calculate the total resistance of resistors in parallel?

73 Answer 36

74 Ques3on 37 What is meant by internal resistance?

75 Answer 37 There resistance provided by a source of EMF (balery or cell)

76 Ques3on 38 What is meant by the term terminal PD?

77 Answer 38 The PD across the terminals of a balery

78 Ques3on 39 What is the equa3on for EMF including internal resistance?

79 Answer 39 EMF=i(R+r)

80 Ques3on 40 What does a poten3al divider do?

81 Answer 40 A circuit containing 2 components designed to divide the PD up into propor3on to their resistor

82 Ques3on 41 How does the resistance of an LDR change as the light intensity increases?

83 Answer 41 As intensity increases resistance decreases

84 Ques3on 42 Describe an advantage of using data loggers

85 Answer 42 Measurements taken at correct 3me, does not need person there, automa3c readings, less human error

86 Ques3on 43 Describe what a longitudinal wave is

87 Answer 43 Waves where the oscilla3ons are parallel to the direc3on of travel

88 Ques3on 44 Describe what a transverse wave is

89 Answer 44 Waves where the oscilla3ons are perpendicular to the direc3on of travel

90 Ques3on 45 Describe what the amplitude and displacement of a wave is

91 Answer 45 Amplitude = maximum displacement of a point from its rest posi3on

92 Ques3on 46 Describe what frequency and period are for a wave

93 Answer 46 The number of oscilla3ons per unit 3me. The 3me taken for one complete palern of oscilla3on

94 Ques3on 47 What is the wave speed equa3on?

95 Answer 47

96 Ques3on 48 Explain what is meant by refrac3on for light

97 Answer 48 Where light changes direc3on when moving from one medium into another due to a difference in density and wave speed

98 Ques3on 49 Explain what is meant by reflec3on for light and sound

99 Answer 49 Where the wave reflects from a surface

100 Ques3on 50 Explain what is meant by diffrac3on of light and sound

101 Answer 50 Where a wave spreads out when passing around an object or through a gap