An undersea cable carries electrical power from the mainland to an island. On the mainland, an ideal transformer receives 6.0 MW6.0\ \mathrm{MW}6.0 MW at a primary potential difference of 15 kV15\ \mathrm{kV}15 kV. Its primary coil has 400 turns and its secondary coil has 10000 turns. The power dissipated by heating in the cable is 6.4 kW.
What is the total resistance of the cable?
0.040 Ω0.040\ \Omega0.040 Ω
23 400 Ω23\,400\ \Omega23400 Ω
25 Ω25\ \Omega25 Ω
400 Ω400\ \Omega400 Ω
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.