An offshore wind farm transfers an input power of 24 MW24\ \mathrm{MW}24 MW to the coast at a transmission potential difference of 120 kV120\ \mathrm{kV}120 kV.
The cable specification allows a maximum heating loss of 80 kW.
Four cable designs are available.
| Cable design | Total resistance |
|---|---|
| J | 0.50 Ω |
| K | 1.0 Ω |
| L | 2.0 Ω |
| M | 4.0 Ω |
Which cable design has the greatest total resistance that keeps the power dissipated in the cable within this limit?
Cable J, with a total resistance of 0.50 Ω0.50\ \Omega0.50 Ω
Cable K, with a total resistance of 1.0 Ω1.0\ \Omega1.0 Ω
Cable L, with a total resistance of 2.0 Ω2.0\ \Omega2.0 Ω
Cable M, with a total resistance of 4.0 Ω4.0\ \Omega4.0 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.