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GCSE Physics > Electricity > Flashcards

Electricity Flashcards

1
Q

Purpose of fuse

A

If too much current passes through it it melts which breaks the circuit
Prevents device from being damaged (from too much current flowing through it)

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2
Q

What does the fuse do if too much current is passing through it

A

Melts
(Breaks circuit to prevent device being damaged from too high current)

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3
Q

Which part of a plug has a voltage of 230V

A

Live wire

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4
Q

Potential difference of Earth and Neutral wire

A

0V

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5
Q

What colour is the Earth wire

A

Green and yellow

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6
Q

What colour is the neutral wire

A

Blue
(Think water is neutral in chemistry and the sea (water) is blue)

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7
Q

What colour is the live wire

A

Brown

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8
Q

Equation linking charge current and time

A

Charge = current x time (QIT)

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9
Q

What is current

A

Rate of flow of charge
(Flow of charge per second)

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10
Q

Equation linking potential difference, current and resistance

A

Potential difference = current x resistance
V=IR

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11
Q

What does it mean if a circuit component is ohmic

A

Current flowing through it directly proportional to potential difference across it

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12
Q

Relationship between current and potential difference of a resistor (meaning when resistance is constant)

A

Directly proportional
As current doubles, potential difference also doubles as V= IR

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13
Q

True or false, in a parallel circuit the current on all the paths adds up to the current in the battery

A

True

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14
Q

True or false in a parallel circuit the potential difference is the same as the battery at each path

A

True

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15
Q

What’s different between current in parallel and series circuit

A

Series- same everywhere
Parallel- current from each path adds up to total current of battery

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16
Q

What’s difference between potential difference in parallel and series circuit

A

Series- potential difference of battery split between all components
Parallel- all components (paths) have same potential difference as battery

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17
Q

Rule for resistance and potential difference in series circuit

A

Total resistance = resistance of all components added together
Total potential difference (battery) = potential difference across all components added together

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18
Q

Which type of current only flows in one direction

A

Direct current (DC)

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19
Q

What type of current is the mains electricity

A

Alternating
(Keeps changing direction)

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20
Q

Frequency of mains electricity

A

50Hz

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21
Q

Power is the…

A

Energy transferred per second

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22
Q

Role of plastic case on device

A

Insulates it to prevent you getting an electric shock

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23
Q

How do step up transformers improve efficiency

A

Higher potential difference means less current needed as power= current x potential difference
Low current means less power wasted from heating of cables as power lost = current squared x resistance

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24
Q

Why does potential difference need to be decreased by step down transformers before reaching homes

A

To make it safe to use

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25
Q

Why is copper commonly used in wires

A

Good conductor
Can bend easily

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26
Q

Which way does current flow

A

Positive to negative side of battery
(Opposite to electrons why flow from negative to positive)

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27
Q

When plotting a graph to show relationship between current and potential difference when resistance is constant, what goes on each axis

A

Y axis is current
X axis is potential difference

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28
Q

Relationship between current and potential difference when resistance in constant

A

Directly proportional.
If one doubles so does the other as V=IR (potential difference = current x resistance)

29
Q

One thing assumed for current and potential difference being directly proportional when resistance is constant

A

Temperature is constant
(Increasing temperature increases resistance)

30
Q

Relationship between current and resistance for filament lamp (light bulb)

A

At higher voltages resistant is higher so there is less current
(F shape)

31
Q

At higher voltages for a filament lamp why is there an increase in resistance

A

More current flowing increases temperature and higher temperature increases resistance

32
Q

Why does a filament lamp not follow ohms law

A

Current and potential difference through lamp aren’t directly proportional
At higher voltages there is less current (but more resistance as the component heats up)

33
Q

How many directions does current flow through a diode in

A

Only 1 direction

34
Q

True or false, current can only flow through a diode in 1 direction

A

True

35
Q

Which component has a very high resistance in the reverse direction which is why current flows through it in only 1 direction

A

Diode

36
Q

3 ways to increase resistance of wire

A

Make wire longer
Make wire thinner
Make wire hotter

37
Q

In a … circuit the components are all in one continuous loop

A

Series circuit

38
Q

Big downside of series circuits

A

If one component breaks/ gets damaged then whole circuit will stop working as electrons can’t pass through

39
Q

Which circuit does Vtotal= V1 + V2 + V3 apply to and what does it mean

A

Series
Total voltage of power pack is shared across all components
(Potential difference if all components will add up to potential difference of battery)

40
Q

In what curcuit is current the same everywhere

A

Series

41
Q

Rule for resistance in series circuit

A

Total resistance = resistance of all components added together

42
Q

True or false, according to ohms law, in a series circuit components with a higher resistance have a higher voltage

A

True
As current is the same everywhere (constant) and V = IR so a greater V needs a greater R

43
Q

Why are parallel circuits more useful than series circuits

A

Have more than 1 loop
If a component breaks, the current can still flow to other components

44
Q

Rule for potential difference in parallel circuit

A

Potential difference is the same everywhere
All components (paths) have same potential difference as battery

45
Q

Rule for current in parallel circuit

A

Current Split between each path
Current of all paths added together= total current

46
Q

Rule for resistance in parallel circuit

A

Adding resistors decreases total resistance

47
Q

For which type of circuit does adding resistors decrease total resistance

A

Parallel
(Opposite for series where more resistors increases total resistance)

48
Q

What is the national grid

A

Giant network of transformers and wires that distribute electricity from power stations to homes

49
Q

Role of Earth wire

A

Stops appliance becoming live which could cause an electric shock
Redirects current to the ground if there’s a fault

50
Q

Conventional current meaning

A

In circuits current flows from positive to negative end of battery

51
Q

What does the Earth wire connect to

A

Case of device

52
Q

Electric field meaning

A

Area around charged object where a force would be exerted onto other charged objects

53
Q

What happens when 2 insulators are rubbed together

A

Friction occurs, electrons transfer from one to another giving them both an overall charge (positive if electrons lost or negative if electrons build up)

54
Q

Why won’t static electricity work on conductors

A

Charge flows through so can’t build up

55
Q

Why won’t static electricity work on conductors

A

Charge flows through so can’t build up

56
Q

Static electricity meaning

A

Build up of charge on 2 insulators

57
Q

Variables in measuring resistance of long wire RPA

A

Dependent = resistance of wire
Independent= length of wire
Control- temperature of wire (Turn off power pack between readings and use low potential difference), material of wire

58
Q

Method for measuring resistance of long wire RPA

A

DV- resistance of wire
IV- length of wire
CV- wire material and temperature

1)Attach the resistance wire to a ruler in series to measure its length
2) Set up a circuit by using crocodile clips to attach the power pack and ammeter in series to the resistance wire in a single loop (first one crocodile clip should be at 10cm, the other at 0cm)
4)Then connect the voltmeter to the resistance wire in parallel.
5) turn on the power pack, immediately record potential difference and current then turn off.
6) Move the 10cm crocodile clip along to 20cm and repeat step 5
7) keep doing this up to 50cm
8) use potential difference and current to calculate resistance of wire at each length with equation resistance = potential difference/ current
9) plot results on graph (resistance on y axis, length on x axis)

59
Q

2 values needed to calculate resistance of wire in RPA

A

Potential difference, current
As resistance = potential difference/ current

60
Q

In measuring resistance of wire RPA why does the power pack need to immediately be turned off inbetween readings

A

Prevents wire heating and increasing resistance due to heat (keeps it a fair test)

61
Q

True or false, a higher resolution is more accurate

A

True

62
Q

What type of error is a zero error

A

Systematic (human)

63
Q

Zero error meaning

A

When an instrument doesn’t read zero when the quantity to be measured is zero

64
Q

For resistance RPA why must you use a low potential difference

A

Prevent wire getting too hot which could burn you

65
Q

Why does an increase in temperature increase resistance

A

As wire gets hot ions in wire vibrate faster
More collisions with electrons
Electrons can’t flow as easily

66
Q

What type of error could cause the ammeter/ voltmeter readings to be too high in resistance RPA

A

Zero error
Length of wire doesn’t start at 0

67
Q

How to calculate energy for SHC RPA with voltmeter and ammeter

A

Power= current x potential difference
Power x time = energy transferred

68
Q

Specific heat capacity variables

A

IV- temperature of block
DV- energy transferred
CV- mass of block, material of block

69
Q

How to set up RPA for testing electrical components

A

In series place ammeter, component and power pack
Add voltmeter around component in parallel

GCSE Physics (13 decks)

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