Topic 2 Electricty In The Home Flashcards
Two types of current
Alternating current
Direct current
What supplies ac
Mains
What supply dc
Battery
What is the current like In ac supplies
Constantly changing direction
What are alternating currents produced by
Alternating voltages in which positive and negative ends keep alternating
What kind of supply is the UK mains supply
An alternating current supply at around 230 V
What is the frequency of the AC mains supply
50 cycles per second or 50 Hz
What is a direct current
Occurrence that is always flowing in the same direction and is created by a direct voltage
How many wires do most electrical appliance have that connect them to the main supply
Three core cable is each with a core of copper in a coloured plastic coating
What does the colour of insulation on each cable show
It’s purpose
Why are the colours always the same for every appliance
So that is easy to tell the different wires apart
What colour is the live wire
Brown
What is the live wire
Provides the alternating potential difference (about 230 V) from the main supply
What colour is the neutral wire
Blue
What is the neutral wire
completes the circuit
when the appliance is operating normally, the current flows through the live and the neutral wires (it’s around 0 V)
What colour is the Earth wire
Green and yellow
What is the Earth wire for
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
As the body is 0 V what happens when you touch a live wire
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
Why is there still a risk of electric shock even if a plug socket or light switch is turned off
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
Any connection between LiveWire an earth can be dangerous if a link creates a low resistance after earth what will happen
A huge current will flow which could result in a fire
What happens during an electric shock
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
