Mains Electricity Flashcards
What does AC mean?
Alternating Current.
This is current which is constantly
changing between a negative and a
positive maximum.
What does DC mean?
Direct Current.
This is current which takes a constant
value.
Is mains electricity an AC supply or a DC supply?
What do each of these stand for?
Mains electricity is an AC supply
What is meant by the frequency of a supply?
This is the rate at which an AC current
changes
What is the frequency and voltage of the UK mains
electricity supply?
● Frequency: 50 Hz
● Voltage: 230V
What type of current do batteries and cells supply?
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 (striped)
Explain when the Earth wire does and doesn’t carry
a current
● Under normal circumstances, no current
flows through the Earth wire
● Current flows when a fault occurs in the
appliance (such as a surge or the casing
becoming live)
What potential is the neutral wire at?
0 volts
State the potential difference between the live and
earth wires
230 Volts
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 becomes touches the casing, the
current will flow through the Earth 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 wire?
In can result in a current surge, causing
electrical shocks.
