A power station supplies 100 MJ100\ \mathrm{MJ}100 MJ of electrical energy to each of two transmission systems. The table shows the energy reaching the receiving substation.
| Transmission system | Energy received / MJ\mathrm{MJ}MJ |
|---|---|
| Lower-voltage system | 88 |
| Higher-voltage system | 97 |
Which statement gives the reduction in energy lost when the higher-voltage system is used, and identifies the transformer needed to reduce its voltage for local distribution?
3 MJ3\ \mathrm{MJ}3 MJ less energy is lost; a step-down transformer is needed.
9 MJ9\ \mathrm{MJ}9 MJ less energy is lost; a step-up transformer is needed.
9 MJ9\ \mathrm{MJ}9 MJ less energy is lost; a step-down transformer is needed.
12 MJ12\ \mathrm{MJ}12 MJ less energy is lost; a step-up transformer is needed.
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.