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13.2 Transformers and the National Grid

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Question 29
H

A power station generates 500 MW500\ \text{MW}500 MW of electrical power. The power could be transmitted at 25 kV25\ \text{kV}25 kV or at 400 kV400\ \text{kV}400 kV.

The transmission cables have a total resistance of 0.50 Ω.

a.

Calculate the current in the cables when the power is transmitted at 400 kV400\ \text{kV}400 kV.

[2]
b.

Calculate the power wasted in the cables when the power is transmitted at 400 kV400\ \text{kV}400 kV.

[2]
c.

Show that the power wasted in the cables at 25 kV25\ \text{kV}25 kV is 256 times greater than the power wasted at 400 kV400\ \text{kV}400 kV.

[3]
d.

Calculate the percentage of the generated power that is wasted in the cables when the power is transmitted at 400 kV400\ \text{kV}400 kV.

[2]
Markscheme

13.2 Transformers and the National Grid Questions

  1. GCSE
  2. /Physics
  3. /13.2 Transformers and the National Grid

108 exam-style questions on Edexcel GCSE Physics 13.2 Transformers and the National Grid, covering 13.2.1 Transformers and induction, 13.2.2 The transformer turns-ratio equation, 13.2.3 The National Grid, 13.2.4 The transformer power equation, and 13.2.5 Advantages of high-voltage transmission. Each one has a worked solution and a mark scheme showing where the marks go.

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