P2 - Electricty - Revision - GCSE Flashcards

1
Q

Keywords
Define voltage

A

Energy per charge

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2
Q

Keywords
Define current

A

The rate of flow of charge

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3
Q

Keywords
Define plug

A

Connects appliances to the mains

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4
Q

Keywords
Define earth wire

A

Safety wire that prevents an appliance becoming live by redirecting excess current to the ground

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5
Q

Keywords
Define neutral wire

A

Completes the circuit

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6
Q

Keywords
Define live wire

A

Carries electricity from the mains to the appliance

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7
Q

Keywords
Define static electricity

A

Charge that accumulates on an insulated object due to things such as friction

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8
Q

Keywords - circuit components
Bulb

A

Lights up when current passes through

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9
Q

Keywords - circuit components
Voltmeter

A

Measures potential difference (in volts)

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10
Q

Keywords - circuit components
Ammeter

A

Measures current (in amps)

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11
Q

Keywords - circuit components
Cell/battery

A

Provides a potential difference in a circuit

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12
Q

Keywords - circuit components
Switch

A

Turns circuit on and off by breaking or completing it

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13
Q

Keywords - circuit components
Resistor

A

Provides resistance - making it more difficult for current to flow

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14
Q

Keywords - circuit components
Variable resistor

A

Provides a changeable resistance

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15
Q

Keywords - circuit components
Fuse

A

Heats up and melts, breaking the circuit, when current is too high

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16
Q

Keywords - circuit components
Diode

A

Keeps current flowing in one direction

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17
Q

Keywords - circuit components
Thermistor

A

Changes resistance based on temperature, decreasing resistance when temperature increases

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18
Q

Keywords - circuit components
Light dependent resistor

A

Changes resistance based on light, resistance decreases when light intensity increases

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19
Q

Keywords - circuit components
Have you revised circuit symbols?

A

Yes

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20
Q

Circuits - properties
What is the equation for current, charge and time? (Hint: derive it from the definition of current)
Give units as well

A

I = Q / t
I - Amps
Q - Coulombs (C)
t - time (s)

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21
Q

Circuits - properties
What does charge do?

A

Carries energy from the battery to circuit components

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22
Q

Circuits - properties
What is the bread - bakery model of circuits?

A

Bread goes from bakery to shop on vans and roads in the same way charge travels round a circuit to components

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23
Q

Circuits - properties
Define a parallel circuit

A

A circuit in which there is more than one pathway for current to flow

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24
Q

Circuits - properties
Define series circuit

A

A circuit where there is one pathway for current to flow

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25
Q

Circuits - properties
What happens to current in a series circuit?

A

Stays equal throughout

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26
Q

Circuits - properties
What happens to current in a parallel circuit?

A

It splits across branches

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27
Q

Circuits - properties
What happens to potential difference in a series circuit?

A

It splits across components

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28
Q

Circuits - properties
What happens to potential difference across a parallel circuit

A

It stays equal on each branch

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29
Q

Circuits - properties
What is the total resistance in a series circuit?

A

Sum of each resistors’ resistances

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30
Q

Circuits - properties
What is the sum of resistance in a parallel circuit?

A

Less than the resistance of the smallest resistor

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31
Q

Circuits - properties
Give the equation for voltage (hint: it is derivable from the definition of voltage)
And give units

A

V = E/Q
V - volts - V
E - Energy - Joules - J
Q - Charge - Coulombs - C

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32
Q

Circuits - properties
What is ohms law (equation and explanations)
Give units as well

A

V = I R
V - volts - V
I - Current - Amps - A
R - resistance - Ohms - Ω
Voltage is directly proportional to current with constant current (and proportional to resistance with constant current)
Resistance is inversely proportional to current

33
Q

Circuits - properties
Give the 2x equations for power and the equation you use to derive it
Give units as well

A

P = I V
P = E / t
P - Watts - W
I - Current - Amps - A
V - Voltage - Volts - V
P = I squared x Resistance
I - current - Amps
Resistance - Ohms - Ω

34
Q

Required practicals - resistance and length of wire
What are the independent, control and dependent variables in the investigation?

A

Independent - length of wire
Dependent - resistance
Control - current, voltage, wire temperate and thickness

35
Q

Required practicals - resistance and length of wire
Write the method for this investigation

A

Fix crocodile clips to bare wire 10 cm apart
Get ammeter and voltmeter readings (to find initial resistance)
Disconnect the circuit and increase the distance between the crocodile clips by 10cm - wait 10 secs
Connect and get ammeter and voltmeter readings
Repeat until 100cm
Draw a graph of voltage and current (voltage on y axis as resistance should be the gradient)

36
Q

Required practicals - resistance and length of wire
What should the conclusion of the investigation be?

A

Resistance and length of wire are directly proportional (as length of wire increases so does resistance)

37
Q

Required practicals - ohms law on a resistor
What components do you need to set up this circuit?

A

Resistor, variable resistor, voltmeter attached in parallel on the resistor, battery, switch

38
Q

Required practicals - resistance and length of wire
True or false: you should connect the voltmeter in parallel measuring the potential difference of the bare wire in the investigation

A

True

39
Q

Required practicals - ohms law on a resistor
Write a method for this investigation

A
  1. Set variable resistor on lowest resistance
  2. Record voltage and ammeter readings
  3. Increase resistance incrementally (1 Ω segments)
  4. Repeat at least 6 times
    Plot the graph
40
Q

Required practicals - ohms law on a resistor
What should the conclusion of this investigation be?

A

That ohms law applies on a resistor (it is an ohmic conductor)

41
Q

Required practicals - resistance in series vs parallel circuits
What components to you need in this circuit

A

Resistance x 2, voltmeter, ammeter, switch, battery

42
Q

Required practicals - resistance in series vs parallel circuits
What is the independent, control, dependent variable in the investigation

A

Independent - arrangement of the resistors
Control - resistor, battery, voltage, length of wire
Dependent - total resistance in the circuit

43
Q

Required practicals - resistance in series vs parallel circuits
Write the method for the investigation

A
  1. Take a reading of current and voltage in a series arrangement
  2. Take the same readings in a parallel arrangement
  3. Compare results
44
Q

Required practicals - resistance in series vs parallel circuits
What should the conclusion be for the investigation?

A

Resistance is higher in a series circuit (sum of resistance of resistors) than parallel (less than the lowest resistor)

45
Q

Required practicals - Ohms law in different components
Does a bulb follow ohms law - draw the graph of a filament bulb and plot voltage and current

A

No

46
Q

Required practicals - Ohms law in different components
Why doesn’t a bulb follow ohms law

A

It heats up and this increases resistance through the movement of positive metal ions preventing the movement of electrons throughout the circuit

47
Q

Required practicals - Ohms law in different components
Does a diode follow ohms law

A

No

48
Q

Required practicals - Ohms law in different components
Why doesn’t a diode follow ohms law - draw a graph of it with respect to voltage and current

A

It has very high resistance in one direction, so current is zero there. It also high high resistance at low potential differences, which means current stays low initially

49
Q

Required practicals - Ohms law in different components
What is one hazard which is pretty much universally applicable when talking about investigations

A

Hazard - hot wire
Consequence/risk - burns skin
Precaution / control measure - don’t touch the wire when the circuit is connected and allow it to cool

50
Q

Exam - Required practicals - Ohms law in different components
How do you structure questions that ask about how to minimise risk or take precautions in experiments

A

To prevent (risk) … which would cause (hazard) … we should (preventative measure) …

51
Q

Plugs + mains
What are pins made of in a plug? Why?

A

Brass - tough, durable, conducts electricity, doesn’t rust!!!

52
Q

Plugs + mains
What are wires made of?- why?

A

Copper - conducts electricity, bends and is ductile, cheaper than alternatives like gold

53
Q

Plugs + mains
What is the casing of a plug made of - why?

A

Plastic - doesn’t conduct (insulator), durable and tough

54
Q

Plugs + mains
What colour is an earth wire

A

Striped yellow and green

55
Q

Plugs + mains
What is the colour of a neutral wire

A

Blue

56
Q

Plugs + mains
What is the colour of a live wire

A

Brown

57
Q

Plugs + mains
Where does the earth wire go

A

Top - think striped (see. Mindmap)

58
Q

Plugs + mains
Where does the live wire go

A

Right - see mindmap for rule

59
Q

Plugs + mains
Where does the neutral wire go

A

Left - see mindmap for rule

60
Q

Plugs + mains
What are the 3 main ratings of fuses

A

3 A, 5 A and 13 A

61
Q

Plugs + mains
What is the rating of a fuse

A

The maximum current that can go through a fuse without it blowing

62
Q

Plugs + mains
What is it called when a fuse heats up and melts

A

The fuse has blown

63
Q

National grid
What is the first stage of the grid (and bonus for its voltage)

A

Power station - 25kV

64
Q

Plugs + mains
What is a step up transformer and why does it do what it does

A

Increases voltage, decreasing current to make the system more efficient - as it prevents energy dissipating into the surroundings

65
Q

Plugs + mains
True or false: pylons and cables have high current and low voltage - with a voltage of 132 kV

A

False (it is the opposite) - however the voltage is still 132 kV

66
Q

Plugs + mains
What does a step down transformer do and why?

A

Increases current and decreases voltage, to make voltage safe

67
Q

Plugs + mains
What is the voltage of the mains

A

230V

68
Q

Plugs + mains
What is a power station definition

A

Generates electricity which is then transported around the country

69
Q

Plugs + mains
What are pylons

A

They support electric cables

70
Q

Plugs + mains
What do cables do

A

Transports electricity around the country

71
Q

Plugs + mains
What is the role of transformers

A

Increases and decrease voltage at particular stages in the national grid

72
Q

Plugs + mains
Give 3 pros of overhead cables

A

Cheap and efficient, easy to repair, can cross roads and canals easily

73
Q

Plugs + mains
What are 3 cons of overhead cables

A

Visual pollution, prone to decay, takes up space

74
Q

Plugs + mains
What is one pro of underground cables and find a bonus one

A

No visual pollution - and decays less easily than overhead cables

75
Q

Plugs + mains
What are 3 cons of underground cables

A

Expensive, difficult to repair, difficult to bury around canals and roads

76
Q

Static electricity
What is static electricity

A

Charge that accumulates on insulators due to forces like friction

77
Q

Static electricity
How can static electricity be produced?

A

Rubbing materials together - this means some negative charge is lost from one material as it is dislodged by the force of friction, and given to another

78
Q

Static electricity
Which way does a positive electric field point

A

Outwards