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13.2 Transformers and the National Grid

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Question 7

A long pair of cables carries electrical power to a tunnel-boring machine several kilometres from the supply. At the supply end, an ideal transformer has 240 turns on its primary coil, which is connected to a 15 kV15\ \mathrm{kV}15 kV alternating supply. The transformer sends 6.0 MW6.0\ \mathrm{MW}6.0 MW into the cables, which have a total resistance of 4.0 Ω.

The power dissipated by heating in the cables is 40 kW.

How many turns are there on the secondary coil of the transformer?

[1]
A

240240240 turns

B

960960960 turns

C

384038403840 turns

D

606060 turns

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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