the national grid - SP13 Flashcards
what is the national grid?
a system of wires and cables
where is energy loss highest in the national grid?
transmission lines
what happens if voltage of electricity passing through a wire is increased?
current decreases
what happens when the current is smaller?
less energy is transferred by heating + efficiency is improved
at what voltage do power stations produce electricity at?
25 kV
what cahnges the voltage from 25kV to 400kV?
transformers
what does a step up transformer do?
increases the voltage and decreases the current at the same time
what does a step down transformer do?
makes the voltage lower and current higher
what is a transformer made up of?
a primary coil, secondary coil (both insulated wire) and a iron core
where is electricity supplied to in a transformer?
primary coil
how do primary and secondary coils differ?
they will have a different voltage and a different amount of turns of the wire round the core
what factor is needed for transformers to work?
alternating current
how does a transformer produce an alternating current?
alternating current in the primary coil creates a continuously changing magnetic field. the iron core of the transformer carries this magnetic feild to the secondary coil. -> the changing magnetic field induces a changing potential difference in the secondary coil
