Topic 2 Electricty In The Home

Question 1

Two types of current

Answer 1

Alternating current
Direct current

Question 2

What supplies ac

Answer 2

Mains

Question 3

What supply dc

Answer 3

Battery

Question 4

What is the current like In ac supplies

Answer 4

Constantly changing direction

Question 5

What are alternating currents produced by

Answer 5

Alternating voltages in which positive and negative ends keep alternating

Question 6

What kind of supply is the UK mains supply

Answer 6

An alternating current supply at around 230 V

Question 7

What is the frequency of the AC mains supply

Answer 7

50 cycles per second or 50 Hz

Question 8

What is a direct current

Answer 8

Occurrence that is always flowing in the same direction and is created by a direct voltage

Question 9

How many wires do most electrical appliance have that connect them to the main supply

Answer 9

Three core cable is each with a core of copper in a coloured plastic coating

Question 10

What does the colour of insulation on each cable show

Answer 10

It’s purpose

Question 11

Why are the colours always the same for every appliance

Answer 11

So that is easy to tell the different wires apart

Question 12

What colour is the live wire

Answer 12

Brown

Question 13

What is the live wire

Answer 13

Provides the alternating potential difference (about 230 V) from the main supply

Question 14

What colour is the neutral wire

Answer 14

Blue

Question 15

What is the neutral wire

Answer 15

completes the circuit
when the appliance is operating normally, the current flows through the live and the neutral wires (it’s around 0 V)

Question 16

What colour is the Earth wire

Answer 16

Green and yellow

Question 17

What is the Earth wire for

Answer 17

For protecting the wiring and for safety
it stops the appliance casing for becoming live
it doesn’t usually carry current only when there is a fault
it’s also at 0 V

Question 18

As the body is 0 V what happens when you touch a live wire

Answer 18

A large potential difference is produced across your body and current flows through you causing a large electric shock which could injure or even kill you

Question 19

Why is there still a risk of electric shock even if a plug socket or light switch is turned off

Answer 19

A current isn’t flowing there but still a potential difference in the live wire
if you make contact with the live wire your body will provide a link between the supply and the Earth so current will flow through you

Question 20

Any connection between LiveWire an earth can be dangerous if a link creates a low resistance after earth what will happen

Answer 20

A huge current will flow which could result in a fire

Question 21

What happens during an electric shock

Answer 21

If a person touches the live wire they will get an electric shock if they are connected to the ground
This is because the wire is at 230v and the person is at 0v
Therefore there is a large pd between them
This causes a charge to flow through them and to the earth