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GCSE Physics Paper 1H (AQA) > Electricity > Flashcards

Electricity Flashcards

1
Q

What is electric current?

A

The rate of flow of electrical charge.

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2
Q

What is current measured in?

A

Amperes/amps (A).

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3
Q

How is current measured?

A

Using an ammeter.

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4
Q

What is electric charge measured in?

A

Coulombs (C).

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5
Q

Why is the current the same in all points in a loop?

A

It has no where else to go, as it is in a single, closed loop.

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6
Q

What is the resistance of a component?

A

A measure of how it resists the flow of charge.

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7
Q

What happens when there is a high resistance?

A

It is more difficult for the charge to flow.

The current is lower.

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8
Q

What is resistance measured in?

A

Ohms (Ω).

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9
Q

What is potential difference?

A

Shows the difference in electrical potential from point in the circuit to another.

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10
Q

What happens when there is a high potential difference?

A

The flow of charge through a component is bigger.

The current is bigger.

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11
Q

What is potential difference measured in?

A

Volts (V).

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12
Q

How is potential difference measured?

A

Using a voltmeter.

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13
Q

A non-linear potential difference-current graph may be the result of what? And what may fix this?

A

As the resistance in some resistors is not constant, it can change as the current changes, which may cause this.
This may be fixed by replacing the resistor with an ohmic resistor, where the resistance does change due to other factors.

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14
Q

What is an ohmic conductor?

A

A resistor in which the current is directly proportional to the potential difference at a constant temperature.

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15
Q

What might a resistor appear as on potential difference-current graph?

A

Y=X

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16
Q

What might the potential difference-current graph look like for a filament lamp? What might cause this?

A

‘elongated S’

As current through a filament lamp increases, as does the temperature, which causes the resistance to increase.

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17
Q

What might the potential difference-current graph look like for a diode? What might cause this?

A

The line travels along the X line before peaking off after the origin.
A diode has a very high resistance in the reverse reaction, which is shown with no voltage until after zero.

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18
Q

What happens to a thermistor as the temperature increases?

A

The resistance decreases.

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19
Q

What happens to a light dependent resistor as light intensity increases?

A

The resistance decreases.

20
Q

List qualities of a series circuit.

A

The current is the same throughout each component.
The total potential difference of the power supply is stated between the components.
The total resistance of two components is the sum the resistance of each component.
Adding resistors in series increases the total resistance.

21
Q

List qualities of a parallel circuit.

A

The potential difference across each component is the same.
The total current drawn from the power supply is the sum of the currents through the separate components.
The total resistance of two resistors is less than the resistance of the smallest individual resistor.
Adding resistors in parallel reduces the total resistance.

22
Q

What does the power of a device depend on?

A

The potential difference across it.

The current flowing through it.

23
Q

What are qualities of a direct current supply?

A

Has a direct potential difference.

Is the type of current supplied by cells and batteries.

24
Q

What makes a direct current supply’s direction constant?

A

As it has a direct potential difference, this is always positive or always negative which allows for a constant direction.

25
Q

What are qualities of an alternating current supply?

A

Has an alternating potential difference.

Is the type of current used in mains electricity.

26
Q

What makes an alternating current supply’s direction alternating?

A

As it has an alternating potential difference, it alternates from positive to negative, which makes it alternating.

27
Q

What is the voltage of mains electricity in the UK?

A

230V.

28
Q

How many times does the mains electricity in the UK change per second?

A

50 times/frequency of 50Hz.

29
Q

What colour is the live wire?

A

Brown.

30
Q

What is the potential difference of the brown wire?

A

230V.

31
Q

Which of the wires inside a cable are blue?

A

Neutral.

32
Q

What is the potential difference of the neutral wire?

A

0V.

33
Q

What colour is the earth wire?

A

Green and yellow striped.

34
Q

Which of the three wires have a potential difference of 0V?

A

Earth and neutral.

35
Q

What is the purpose of the live wire?

A

Carries current to the appliance.

36
Q

What is the purpose of the neutral wire?

A

Carries current away from the appliance.

37
Q

What is the purpose of the earth wire?

A

It acts as a safety measure and prevents the exterior of the appliance from becoming charged.

38
Q

What is power?

A

The rate of energy transfer or work done.

39
Q

How can you increase the efficiency of an energy transfer?

A

The amount of wasted energy needs to be reduced.

40
Q

What is efficiency the ratio of?

A

Useful energy out to total energy in.

41
Q

How might work be done on the flow of charge?

A

Whenever a charge flows, it has to overcome resistance, which requires energy; therefore work is done.

42
Q

What is the National Grid?

A

A system of cables and transformers linking power stations to homes and businesses.

43
Q

What happens at the power station?

A

The energy supply to transferred into electrical energy.

Most plants use steam turbines to generate this electricity.

44
Q

What happens at step-up transformers?

A

The transformers increase the potential difference.
It reduces the current and therefore the wasted heat energy which would have generated.
Due to this, the transmission is now more efficient.

45
Q

What do transmission cables do?

A

Transfer electricity.

46
Q

What happens at step-down transformers?

A

Reduce potential difference down to an acceptable value for domestic use.

GCSE Physics Paper 1H (AQA) (4 decks)

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