A car rear-window demister has four conducting strips. The table shows the current in each strip and the resistance of each strip on the normal setting.
| Strip | Current in A\mathrm{A}A | Resistance in Ω\OmegaΩ |
|---|---|---|
| P | 1.5 | 8.0 |
| Q | 2.0 | 4.0 |
| R | 2.5 | 2.0 |
| S | 3.0 | 1.0 |
On the fast setting, the current in every strip is 20% larger than on the normal setting. The resistance of each strip does not change. The manufacturer will inspect any strip that dissipates more than 24 W on the fast setting.
Use the data to determine which strip, if any, the manufacturer should inspect. Justify your answer.
105 exam-style questions on Edexcel GCSE Physics 10.3 Electrical energy and power, covering 10.3.1 The heating effect of an electric current, 10.3.2 Reducing energy transfer in wires, 10.3.3 Advantages and disadvantages of the heating effect, 10.3.4 Energy transferred by an electrical circuit, 10.3.5 Electrical power, and 10.3.6 Energy transfers in domestic devices. Each one has a worked solution and a mark scheme showing where the marks go.