Complete the following sentence using one of the phrases from the box below.
To ensure safety and compatibility with domestic appliances, the extremely high potential difference used in the long-distance transmission lines of the national grid is reduced to a lower voltage at local substations using _________.
28 exam-style questions on Edexcel GCSE Physics 13.2 Transformers and the National Grid. Each one has a worked solution and a mark scheme showing where the marks go.