Unit 2: Electricity (Mains Electricity)

Question 1

Power

Answer 1

The rate of energy transfer/amount of energy transferred per second. Power = Current x Voltage

Question 2

Fuse

Answer 2

A safety device consisting of a thin metal filament in a glass cylinder that melts and cuts off the power supply if there is a surge in current. Fuses are connected to the live wire.

Question 3

Fuse component

Answer 3

Glass cylinder containing a thin metal wire

Question 4

If current too large

Answer 4

The wire heats up & melts, causing the wire to break, breaking the circuit & stopping current

Question 5

Energy transferred equation

Answer 5

E = I x V x t

Question 6

Electrical safety

Answer 6

Double insulation, Earthing, Fuses, Circuit breaker

Question 7

Circuit breaker

Answer 7

A safety device with an automatic switch that cuts off the power supply if a surge of current passes through it.

Question 8

Advantages circuit breakers

Answer 8

• Doesn’t melt & break, therefore it can be reset & reused
• Faster

Question 9

DC

Answer 9

A steady current which constantly flows in one direction and has a fixed posivite terminal & fixed negative terminal; cell/battery

Question 10

AC

Answer 10

A current that constantly changes its direction; 2 identical terminals

Question 11

Insulator

Answer 11

A material that doesn’t allow electrical charge to flow