A biomass power station supplies a paper mill through a private transmission link. The station provides a constant electrical power of 75 MW75\ \text{MW}75 MW to the link.
The engineers can operate the link using either of the settings shown in the table.
| Quantity | Value |
|---|---|
| lower transmission potential difference | 50 kV50\ \text{kV}50 kV |
| higher transmission potential difference | 250 kV250\ \text{kV}250 kV |
| total resistance of the transmission cables | 1.6 Ω |
Calculate the current carried by the link when the higher potential difference setting is selected.
At the higher potential difference setting, calculate the rate at which energy is dissipated by the transmission cables.
An engineer states that changing from the lower potential difference setting to the higher potential difference setting reduces the power dissipated by the cables by 96%.
Show that the engineer's statement is correct.
Calculate the percentage of the station's electrical output that is dissipated by the cables when the higher potential difference setting is used.
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.