P5: Electricity In The Home

Question 1

Direct current flows______

Answer 1

In one direction only

Question 2

Alternating current:

Answer 2

Repeatedly reverses its direction of flow

Question 3

Why is plastic used in plugs?

Answer 3

Because it is a good electrical insulator

Question 4

What is a mains cable made out of?

Answer 4

Two or three insulated copper wires surrounded by an outer layer of flexible plastic material

Question 5

What happens when a charge flows through a circuit for a given time?

Answer 5

The energy supplied by the battery is equal to the energy supplied by all components of the circuit

Question 6

What does every main curcuit have?

Answer 6

• a live wire

- a neutral wire

Question 7

What are step-up transformers and what do they do?

Answer 7

They are used at power stations to transfer energy to the national grid

They are used to make the size of the alternating potential difference bigger?

(Typically from 25,000 V to about 132,000 V)

Question 8

What are step down transformers and what do they do?

Answer 8

They are used to supply electricity from the national grid to consumers

• homes and offices are provided with the same power as a 230V direct current.
• factories are supplied with a potential difference of 33kv-100kv

Question 9

Why is the step up transformer important?

Answer 9

Less energy is lost in the cables due the the high potential difference