Electricity Flashcards

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1
Q

State what is meant by AC.

A

A current whose instantaneous value and direction varies with time.

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2
Q

Which circuit component is represented by the following diagram?

A

Variable Resistor

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3
Q

What happens if a positive and a negative charge are brought together?

A

They attract each other

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4
Q

What is the energy change in a lamp?

A

Electrical to light (+ heat)

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5
Q

Name one source of AC

A

Mains supply

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6
Q

What is the rule for current in a series circuit?

A

The current is the same everywhere

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7
Q

What happens if two positive charges are brought together?

A

They repel each other

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8
Q

What is the energy change in a buzzer?

A

Electrical to sound

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9
Q

Which circuit component is represented by the following diagram?

A

Capacitor

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10
Q

What is a Light Dependent Resistor?

A

A resistor whose resistance changes with changes in light level

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11
Q

What is the charge on a proton?

A

Positive

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12
Q

What is current?

A

The charge transferred per second

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13
Q

What would happen to an electron being fired through the electric field below?

A

It would experience a force and be attracted to the positive plate.

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14
Q

How does a relay work?

A
  • Close a switch to make a current flow in a wire.
  • This creates an electromagnet.
  • Electromagnet attracts metal switch.
  • This completes the second circuit and the lamp switches on.
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15
Q

What is the energy change in an LED?

A

Electrical to light

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16
Q

Which device measures voltage?

A

Voltmeter

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17
Q

Which particles are in the nucleus of the atom?

A

Protons and Neutrons

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18
Q

What will be the voltage across a capacitor when it is fully discharged?

A

Zero volts.

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19
Q

What happens if you increase the resistance in a circuit?

A

The current will decrease

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20
Q

Which circuit component is represented by the following diagram?

A

Loudspeaker

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21
Q

What is DC?

A

Direct current. Electrons move in one direction only.

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22
Q

Which component does the symbol represent?

A

Buzzer

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23
Q

Which circuit component is represented by the following diagram?

A

Thermistor

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24
Q

What would the field lines around a positive point charge look like?

A

Field lines show direction away from the positive point charge.

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25
Q

How can you identify a series circuit?

A

It is a circuit with only one path round it.

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26
Q

Name one source of DC

A

Battery

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27
Q

How should a diode or LED be connected with a battery to light correctly?

A

Small line on battery points to small line on LED or diode.

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28
Q

Explain how a fuse works.

A

A fuse is a thin wire. If too much current passes through it, it will get hot and melt. This breaks the circuit.

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29
Q

Which device measures resistance?

A

Ohmmeter

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30
Q

What is electric charge?

A

An electric charge occurs when there are fewer or more electrons than protons.

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31
Q

Which circuit component is represented by the following diagram?

A

Light Emitting Diode

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32
Q

Which circuit component is represented by the following diagram?

A

Light Dependent Resistor

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33
Q

If you heat a conductor, what happens to it’s resistance?

A

It increases

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34
Q

What is the rule for volatges in a parallel circuit?

A

The voltage across each branch is equal to the supply voltage.

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35
Q

Which circuit component is represented by the following diagram?

A

Battery

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36
Q

What does an electric field line show?

A

The direction a positive charge would move in that field.

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37
Q

Which circuit component is represented by the following diagram?

A

Lamp

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38
Q

What is AC?

A

Alternating current. The electrons change direction, moving backwards and forwards, many times in a second.

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39
Q

What is the function of a transistor?

A

Electronic switch

40
Q

What two factors effect the running cost of an appliance?

A

The time it is used for The power rating of the appliance

41
Q

How can a parallel circuit be identified?

A

It is a circuit with more than one path round it.

42
Q

State a device that can be used in a light sensor

A

LDR

43
Q

Which circuit component is represented by the following diagram?

A

Photovoltaic cell / solar cell

44
Q

What is the symbol for a voltmeter?

A

Circle with a V in it

45
Q

What is the energy change in a microphone?

A

Sound to electrical

46
Q

What is the rule for selecting a fuse from a power rating?

A

Appliances less than 720W use a 3A fuse Appliances more than 720W use a 13A fuse

47
Q

How can power losses be reduced in transmission lines?

A

By increasing the transmission voltage and so decreasing teh transmission current. Power loss P = I2R, so if the current is reduced the power lost is reduced.

48
Q

What would the field lines look between parallel plates?

A

Field lines run from positive to negative plate, with a bulge at the ends of the parallel plate.

49
Q

What is power?

A

The energy used per second

50
Q

Which circuit component is represented by the following diagram?

A

Motor

51
Q

Which circuit component is represented by the following diagram?

A

Fuse

52
Q

What is the charge on a neutron?

A

No charge

53
Q

Which device measures current?

A

Ammeter

54
Q

What is the function of a MOSFET?

A

Electronic switch

55
Q

Which circuit component is represented by the following diagram?

A

Transistor

56
Q

For the diagram of the atom name the parts.

A
57
Q

Which circuit component is represented by the following diagram?

A

Microphone

58
Q

How can you tell from this oscilloscope image that this is AC?

A

The trace shows a change in direction

59
Q

How should an ammeter be connected to measure the current in a component?

A

It should be connected in series with the component

60
Q

How can you indicate a stronger electric field?

A

More field lines

61
Q

What happens if you unscrew one of the lamps in the circuit below? Why?

A

The other lamps go out. There is a break in the circuit and the current does not have a complete route to the battery.

62
Q

What is the energy change in a motor?

A

Electrical to kinetic

63
Q

What is the rule for voltages in a series circuit?

A

The voltage across each component added together is equal to the supply voltage.

64
Q

What is the effect of an electric field on a charge?

A

The charge will experience a force.

65
Q

How is a uniform electric field represented?

A

Evenly spaced field lines

66
Q

What is the energy change in a buzzer?

A

Electrical to sound

67
Q

Which circuit component is represented by the following diagram?

A

Resistor

68
Q

What is the charge on an electron?

A

Negative

69
Q

What type of current is represented by this oscilloscope image?

A

DC

70
Q

Which circuit component is represented by the following diagram?

A

Switch

71
Q

What happens if two negative charges are brought together?

A

They repel each other

72
Q

State two place a variable resistor can be used.

A

Light dimmer switch sped control on Scalextric cars volume control on a radio

73
Q

What is meant by capacitance?

A

Charge stored per unit volt

74
Q

What type of current is represented by this oscilloscope image?

A

AC

75
Q

What is the symbol for an Ohmmeter?

A

Circle with an Omega in it

76
Q

What would the field lines around a negative point charge look like?

A

Field lines show direction towards the negative point charge

77
Q

Explain how electrostatics can be used in paint spraying a car.

A

Car is connected to a negative terminal so that it is negatively charged.

Spray gun is made positively charged so the paint particles are positive.

The poistive paint is attracted to the negative car.

Areas of the car already covered in paint will repel any more charged paint.

78
Q

Which circuit component is represented by the following diagram?

A

Cell

79
Q

Which circuit component is represented by the following diagram?

A

MOSFET

80
Q

When would you use a relay?

A

To switch on a high current ciruit using a low current circuit for safety.

81
Q

What is meant by the potential difference (voltage) of a supply?

A

It is the number of Joules of energy given to each coulomb of charge passing through the cell

82
Q

What will be the voltage across a capacitor when it is fully charged?

A

The supply voltage.

83
Q

Why is an LED normally connected in series with a resistor?

A

Resistor is to protect the LED by limiting the current in the LED.

84
Q

What is the symbol for an ammeter?

A

Circle with an A in it.

85
Q

What is the energy change in a photovoltaic cell?

A

Light to electrical

86
Q

What is the rule for current in a parallel circuit?

A

The supply current is equal to the current in each branch added together.

87
Q

What is a thermistor?

A

A resistor whose resistance changes with changes in temperature

88
Q

Name one place that electrostatics can be used.

A
  • Laser printers
  • Paints spraying
  • Cling film
  • Forensic science
  • Dust removal
  • Electrostatic precipitators
  • Electrostatic separators
89
Q

What is the energy chage in a battery?

A

Chemical to electrical

90
Q

Which circuit component is represented by the following diagram?

A

Diode

91
Q

How can you indicate a weaker electric field?

A

Less field lines

92
Q

What is the energy change in a loudspeaker?

A

Electrical to sound

93
Q

What is a fuse?

A

Safety device that protects the flex

94
Q

What is the stated value of the mains?

A

230V, 50Hz

95
Q

What does a capacitor do?

A

Stores charge or energy

96
Q

State a device that can be used in a temperature sensor

A

Thermistor

97
Q

How should a voltmeter be connected to measure the voltage across a component?

A

It should be connected across the component