topic 2 - electricity: domestic uses and safety Flashcards
What type of electricity supply is mains electricity?
Alternating current (ac).
In the UK, what is the frequency of the domestic electricity supply?
50 Herts (Hz)
In the UK, what is the voltage of the domestic electricity supply?
230 Volts (V)
What type of electricity supply is mains electricity?
Alternating current (ac).
What are the 2 types of electricity supply?
Alternating current (ac) and direct current (dc).
Which type of electricity supply is mains electricity?
An ac supply.
What type of electricity supply are cells and batteries?
A dc supply.
What are alternating currents produced by?
Alternating voltages.
What is the difference between alternating and direct potential differences?
In alternating potential differences, the positive and negative ends keep alternating whereas in direct potential differences, they don’t alternate.
In the UK, what is the frequency of the domestic electricity supply?
50 Hz
In the UK, what is the voltage of the mains electricity supply?
230V
How many core cables are appliances connected to the eletricity supply with?
Three.
What does the colour of the insulation of each cable show?
Its purpose.
What colour is the live wire?
Brown.
What colour is the neutral wire?
Blue.
What colour is the earth wire?
Green and yellow stripes.
What does the live wire provide?
The alternating potential difference from the mains supply.
What is the purpose of the neutral wire?
To complete the circuit.
What is the purpose of the earth wire?
It is a safety wire which stops the appliance from becoming live.
When would the earth wire carry current/
If there was a fault - it doesn’t usually carry current.
What is the voltage of the live wire?
230V
What is the voltage of the earth wire?
0V
What is the voltage of the neutral wire?
0V
Why might the live wire be dangerous even when a switch in the main circuit is open?
It can give you an electric shock because even though there is no current flowing, there is still a potential difference in the live wire. If you make contact with the wire, your body would rpovide a link between the supply and the earth and so the current would flow through you.
What is the danger in providing any connection between the live wire and earth?
If the link creates a low resistance path to earth, a huge current will flow, which could result in a fire.
