A transformer supplies a resistance-welding machine in a factory. The transformer is 100% efficient.
| quantity | value |
|---|---|
| primary potential difference | 400 V |
| primary current | 30 A |
| secondary potential difference | 20 V |
Calculate the current delivered to the welding machine.
Use the equation
VpIp=VsIsV_{\mathrm{p}}I_{\mathrm{p}}=V_{\mathrm{s}}I_{\mathrm{s}}VpIp=VsIs
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.