P8.2.4 - Mains electricity

Question 1

What is the difference between the electrical power provided by a battery, and that provided by the mains?​

Answer 1

• Battery has DC Current but the mains have AC current
• A battery has low potential difference but the mains have a high potential difference
• In a battery the current flows in one direction only
• In the mains the current flow continually alternates direction

Question 2

What is Alternating Current?

Answer 2

Electric current which repeatedly alternates direction in a circuit

Question 3

What is Direct Current?

Answer 3

Electric current which flows in one direction only in a circuit

Question 4

Why does current alternate in AC?

Answer 4

Because the p.d. alternates

Question 5

When the current of an AC supply changes directions…

Answer 5

the voltage changes direction

Question 6

What is the live wire?

Answer 6

The wire that is connected to 230V

Question 7

What is the neutral wire?

Answer 7

The wire that is connected to 0V

Question 8

What is the earth wire?

Answer 8

The wire connected to the earth, through which current flows if there is a fault instead of flowing through you

Question 9

What wires do 3 core cables contain?

Answer 9

The live wire, the neutral wire and the earth wire

Question 10

What wires do 2 core cables contain?

Answer 10

The live wire and the neutral wire

Question 11

Compare the wires in a plug

Answer 11

• Current enters an appliance through the live wire (brown).​
• Current leaves an appliance through the neutral wire (blue).​
• Normally, there is no current in the Earth wire (green/yellow).​
• However, in the event of an electrical fault, current is safely conducted to the ground through the Earth wire.​