Electricity is generated at a power station at a potential difference of 25 kV25\ \text{kV}25 kV. It is transmitted through the national grid at 400 kV400\ \text{kV}400 kV, and it is supplied to homes at 230 V.
Explain how the national grid uses transformers to transfer energy efficiently and safely from the power station to homes.
Include ideas about potential difference, current, power and the numbers of turns on the transformer coils in your answer.
16 exam-style questions on OCR GCSE Physics 8.2 Powering Earth, covering 8.2.1 Renewable and non-renewable energy resources, 8.2.2 Patterns and trends in energy use, 8.2.3 The national grid, 8.2.4 Step-up and step-down transformers, 8.2.5 Efficiency of the national grid, 8.2.6 Transformers and power transmission at high voltage, 8.2.7 The UK domestic supply, 8.2.8 Direct and alternating potential difference, 8.2.9 Live, neutral and earth wires, and 8.2.10 Dangers of mains electricity. Each one has a worked solution and a mark scheme showing where the marks go.