Mains Electricity Flashcards
What does AC mean
Alternating current
This is current that constantly changes between positive and negative
What does DC
Direct current
This is current which takes a constant value
What type of supply is mains electricity
Alternating current
What is the frequency of a supply
This is the rate at which an AC current changes
50 Hz
What is the frequency of mains supply
50hz
What is the voltage of mains electricity
230V
What type of current do batteries and cells
Direct current
What is the power rating of an appliance
It shows how much energy a device converts per second
What wires does a typical appliance have
Live wire
Neutral wire
Earth wire
What colour is the live wire
Brown
What colour is the neutral wire
Blue
What colour is the earth wire
Green and yellow stripes
When does apthe earth wire carry a current
Normally it won’t Cary any current
Current only flows through the earth wire when a problem occurs like a surge
What potential difference is the neural wire at
0 volts
What is the potential difference between the live and earth wires
230V
What is the purpose of the neutral wire
To complete the circuit by connecting the appliance back to the mains supply
For metal appliances where is the Earth wire connected to ? Why?
Earth wire is connected to the metal casing of the appliance
If live wire touches the casing the current will flow through the wire preventing electrocution
How does a fuse wire stop the device from getting damaged
When the current becomes too high the fuse wire will melt and break, therefore stopping current from flowing to the appliance and preventing damage
Why is it important to connect a fuse or switch to the live wire
When the switch is turned off, or when the fuse breaks, it will break the circuit and stop current running through the wire . This provides a method to stop current flowing into the appliance
Why is it dangerous to have a connection between the earth wires and the live wires
It can result in a current surge, causing electrical shocks
