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7.3 Induced potential, transformers and the National Grid (HT only)

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Question 10
H

A power station transfers 400 MW of electrical power to the National Grid. The transmission cables have a total resistance of 8.0 Ω.

a.

The power is transmitted at a potential difference of 400 kV. Calculate the current in the transmission cables. Use the equation power=potential difference×current\text{power} = \text{potential difference} \times \text{current}power=potential difference×current.

[2]
b.

The power wasted in heating the cables is given by P=I2RP = I^2 RP=I2R. Explain why transmitting the same power at 132 kV instead of 400 kV would waste much more energy in the cables.

[2]
Markscheme

7.3 Induced potential, transformers and the National Grid (HT only) Questions

  1. GCSE
  2. /Physics
  3. /7.3 Induced potential, transformers and the National Grid (HT only)

40 exam-style questions on AQA GCSE Physics 7.3 Induced potential, transformers and the National Grid (HT only), covering 7.3.1 Induced potential (HT only), 7.3.2 Uses of the generator effect (HT only), 7.3.3 Microphones (HT only), and 7.3.4 Transformers (HT only). Each one has a worked solution and a mark scheme showing where the marks go.

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