# WJEC Physics P1 Topic 2

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• Created by: MrTom
• Created on: 10-01-16 21:30

## The National Grid

The National grid is used to ensure a reliable and efficient supply of electricity by linking power stations using pylons and cables. Having all power sations is really useful because if one breaks down then another can take over. Also, more power can be generated during Peak Demand (above the baseload).

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## Transformers

Step-Up Transformers

Increase the voltage and decrease the current. This makes the energy transfer more efficient because less energy is lost as heat through wires

Step-Down Transformers

Decrease the voltage and increase the current (opposite to above). This makes the electricity a much safer voltage to enter the house

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## Equation

Power (Watts) = Voltage (Volts) x Current (Amps)

The power station generates 500 MW of power, and has a voltage of 40000. Calculate the current

Power (Watts) = Voltage (Volts) x Current (Amps)

500 x 1 x 10 to the power 6 = 40000 x current

current = 500 x 1 x 10 to the power 6 / 40000

current = 1250 A

(1 MW = 1 x 10 to the power 6 W)

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