P2 Mains Electricity Flashcards
What colour is the Earth wire?
Yellow and green
What colour is the live wire?
Brown
What colour is the neutral wire?
Blue
What pd does the neutral wire have?
0V
What pd does the live wire have?
230V
What pd does the Earth wire have?
0V
What is the live pin made from?
Brass
Other than wires what else is in a plug socket?
Live pin, neutral pin, Earth pin, outer casing, cable gripper, fuse
What is the rule for a fuse?
The current should be the next greatest current after the current used by the appliance
How does current work in a plug socket?
Current flows backwards and forwards (alternating current) from the live to the neutral wire (50x a second)
What happens if the live wire touches the casing?
The case becomes live, a large current flows through the case to Earth, heating up the case which can cause a fire. The fuse melts, the circuit is broken and it is safe.
What is the equation for power?
Current x p.d
What are the different fuse sizes (A)?
1,3,5,13,30,50
What is d.c?
Direct current is charge that only flows in one direction.
What is a.c current?
Alternating current repeatedly flows backwards and forwards.
What is the frequency of UK mains?
50Hz
What is the p.d of UK mains?
230V
What is the National Grid?
Nationwide network of transformers and cables that link power stations to homes, offices and other consumers of mains electricity.
What are step up transformers?
Increase the p.d from the power station to the cables
What is a step down transformer?
Decreases p.d so it is safe to use and does not blow electrical appliances
What is the p.d of the transmission cables?
400000V
What do power stations produce?
An alternating current of around 25000V
Why do transformers improve efficiency?
A high p.d across the cables means that a lower amount of current is needed to transfer the same amount of power. Less electrical power is wasted due to heating of the cables.
What is a fuse?
a fuse contains a thin wire that melts and cuts the current off if too much current passes through it.
What are circuit breakers?
an electrical component that interrupts the current in a circuit if there is a fault and the current rises to dangerous levels.
