- electricity is sent around the country through the national grid at the lowest current possible
- high currents cause greater energy losses due to heating in in the cables.
- the energy loss is proportional to P = I^2 x R
- so if the current is doubled, you quadruple the power lost.
- using low resistance cables also reduces power loss.
- P = I x V so a low current means a high voltage for the same amount of power.
- transformers allow for a 400,000V step-up
- has to be stepped down to 230V before home use for safety and insulation issues.
- power station, 25,000V to step-up to pylons, 400,000V to step-down to home, 230V.
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