TRANSFORMERS AND NATIONAL GRIDS
2 marks · EasyElectricity leaves a power station at 25,000 V. A step-up transformer increases the voltage for transmission.
Explain why increasing the voltage is important before transmitting electricity.
What effect does increasing the voltage have on the current in the transmission cables?
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(a) To reduce energy losses due to heating in the cables / minimize energy loss.
(b) Increasing voltage decreases the current.
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Marking points
B1 (a) · 1 mark · Correct explanation: Increasing voltage reduces energy loss in cables (or minimises heating losses).
B1 (b) · 1 mark · Correct effect: Increasing voltage decreases current in the transmission cables.
Worked solution
a) Increasing the voltage before transmission reduces the energy lost as heat, because heat loss is greater at higher currents.
b) Increasing voltage decreases the current required to transmit the same power.