P2 Mains Electricity Flashcards

1
Q

What colour is the Earth wire?

A

Yellow and green

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2
Q

What colour is the live wire?

A

Brown

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3
Q

What colour is the neutral wire?

A

Blue

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4
Q

What pd does the neutral wire have?

A

0V

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5
Q

What pd does the live wire have?

A

230V

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6
Q

What pd does the Earth wire have?

A

0V

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7
Q

What is the live pin made from?

A

Brass

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8
Q

Other than wires what else is in a plug socket?

A

Live pin, neutral pin, Earth pin, outer casing, cable gripper, fuse

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9
Q

What is the rule for a fuse?

A

The current should be the next greatest current after the current used by the appliance

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10
Q

How does current work in a plug socket?

A

Current flows backwards and forwards (alternating current) from the live to the neutral wire (50x a second)

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11
Q

What happens if the live wire touches the casing?

A

The case becomes live, a large current flows through the case to Earth, heating up the case which can cause a fire. The fuse melts, the circuit is broken and it is safe.

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12
Q

What is the equation for power?

A

Current x p.d

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13
Q

What are the different fuse sizes (A)?

A

1,3,5,13,30,50

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14
Q

What is d.c?

A

Direct current is charge that only flows in one direction.

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15
Q

What is a.c current?

A

Alternating current repeatedly flows backwards and forwards.

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16
Q

What is the frequency of UK mains?

A

50Hz

17
Q

What is the p.d of UK mains?

A

230V

18
Q

What is the National Grid?

A

Nationwide network of transformers and cables that link power stations to homes, offices and other consumers of mains electricity.

19
Q

What are step up transformers?

A

Increase the p.d from the power station to the cables

20
Q

What is a step down transformer?

A

Decreases p.d so it is safe to use and does not blow electrical appliances

21
Q

What is the p.d of the transmission cables?

A

400000V

22
Q

What do power stations produce?

A

An alternating current of around 25000V

23
Q

Why do transformers improve efficiency?

A

A high p.d across the cables means that a lower amount of current is needed to transfer the same amount of power. Less electrical power is wasted due to heating of the cables.

24
Q

What is a fuse?

A

a fuse contains a thin wire that melts and cuts the current off if too much current passes through it.

25
Q

What are circuit breakers?

A

an electrical component that interrupts the current in a circuit if there is a fault and the current rises to dangerous levels.