mains electricity

Question 1

How does insulation protect users from electric shocks?

Answer 1

It prevents contact with live wires by covering them with a non-conductive material.

Question 2

What is double insulation, and how does it protect users?

Answer 2

Appliances with double insulation have two layers of insulating material and do not require an earth wire.

Question 3

What is the purpose of earthing in electrical appliances?

Answer 3

It provides a safe path for excess current to flow into the ground, preventing electric shocks.

Question 4

How does a fuse protect an electrical circuit?

Answer 4

If the current gets too high, the fuse wire melts, breaking the circuit and stopping the flow of electricity.

Question 5

How does a circuit breaker work?

Answer 5

It detects excessive current and automatically switches off the circuit to prevent damage.

Question 6

What is the formula for electrical power?

Answer 6

Power (P) = Current (I) × Voltage (V)

Question 7

A hairdryer uses 5 A of current at 230 V. What is its power?

Answer 7

P = 5 × 230 = 1150 W

Question 8

What is the formula for energy transferred in an electrical circuit?

Answer 8

Energy transferred (E) = Current (I) × Voltage (V) × Time (t)

Question 9

A kettle operates at 10 A and 230 V for 2 minutes. How much energy does it transfer?

Answer 9

E = 10 × 230 × 120 = 276,000 J (or 276 kJ)