electricity - mains electricity and the national grid Flashcards
in the uk, how are electrical components connected to the mains supply
via a three core cable
in a three core cable what are the wires made of and why
made of copper as it is a good electrical conductor
what is the brown wire
the live wire
it carries an alternating potential difference from the supply (230V)
what is the live wire connected too
a fue in the plug
what is the blue wire
the neural wire
it completes the circuit
potential difference = 0v compared to the live wire
what is the green and yellow striped wire
the earth wire
this is a safety wire to stop the appliance from becoming live
what is so important about the live wire
it can be extremely dangerous and fatal if touched
why are appliances with a metal case dangerous
because if the wire becomes loose and touches the metal case then the case becomes live
what is the metal case connected too and why is this important
its connected to the earth wire
the earth wire is connected into the ground with a metal rod which is important as if the case becomes live the current flows to the earth and shuts of the current
what does the national grid consist of
transformers and high voltage cables
what does the national gird connect
the power stations to the homes
why is energy always lost in the power cables
how can we reduce it
due to the resistance of the wires
reduced = by building power stations closer to homes or transformers
what is the role of a step up transformer
increase the potential difference to several hundred thousand volts
what happens if the potential difference is very high in the cables
less energy is lost
what is the role of a step down transformer
to reduce the potential difference to around 230 volts
