Same answer chain

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step-up transformer increases the potential difference

For the same power transfer, the current in the transmission cables is reduced

Lower current causes less heating or energy/power loss in the cables

Reduced cable losses make the transfer more efficient

Current question

The potential difference across the primary coil in transformer Y is 400 000 V. The potential difference across the secondary coil is 11 000 V. The current in the primary coil is 660 A. Calculate the current in the secondary coil of transformer Y. Use the Physics Equations Sheet. Current in the secondary coil = A

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Why this earns marks

1 The step-up transformer increases the potential difference.
2 For the same power transfer, the current in the transmission cables is reduced.
3 Lower current causes less heating or energy/power loss in the cables.
4 Reduced cable losses make the transfer more efficient.

Common weak answer: Names the topic but skips the middle reasoning links.