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

Figure 7 shows how the National Grid transfers energy from a power station to some street lamps.

Why is the current in each street lamp less than the current in the secondary coil in transformer Y? Tick () one box. Current is used up in the cables between Y and each street lamp. Some of the current is dissipated to the surroundings. The cables between Y and the street lamps have electrical resistance. The street lamps are connected in parallel.

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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.