2.3 - Domestic Uses & Safety

Question 1

Is Mains electricity alternating or direct current?

Answer 1

Alternating current

Question 2

Is a battery alternating or direct current?

Answer 2

Direct current

Question 3

What frequency is the mains power supply in the UK?

Answer 3

50 Hz

Question 4

What voltage is domestic power supply in the UK?

Answer 4

230V

Question 5

What is the difference between direct and alternating potential difference?

Answer 5

In direct current (DC), charge flows in a constant direction. In alternating current (AC), charge flows back and forth many times per second

Question 6

What is frequency, in an AC circuit?

Answer 6

How many times per second the charge changes direction

Question 7

What cables are inside a mains plug?

Answer 7

Live Wire - Brown Neutral Wire - Blue Earth Wire - Green and Yellow Stripes

Question 8

What does the live wire do?

Answer 8

It carries the alternating potential difference from the power supply

Question 9

What does the neutral wire do?

Answer 9

It completes the circuit back to the power supply

Question 10

What does the earth wire do?

Answer 10

It is a safety wire to stop a metal appliance from becoming itself live (i.e. conducting electricity on to its surroundings)

Question 11

What is the potential difference between the live wire and earth wire?

Answer 11

230V, because the earth wire should be at 0V unless there is a fault.

Question 12

What would happen if the live wire was connected to the earth

Answer 12

The charge would short-circuit and flow directly from the live connection through, and potentially electrocute anyone on the path.