A technician checks the control circuit for a small ventilation fan. The circuit contains a variable resistor in series with a 6.0 Ω fixed resistor.
The readings for two operating settings are shown.
| Setting | Supply potential difference / V\mathrm{V}V | Current / A\mathrm{A}A |
|---|---|---|
| R | 8.0 | 0.40 |
| S | 12.0 | 0.30 |
Which pair gives the resistance of the variable resistor at R and at S, respectively?
14 Ω14\ \Omega14 Ω at R and 40 Ω40\ \Omega40 Ω at S
20 Ω20\ \Omega20 Ω at R and 40 Ω40\ \Omega40 Ω at S
14 Ω14\ \Omega14 Ω at R and 34 Ω34\ \Omega34 Ω at S
20 Ω20\ \Omega20 Ω at R and 34 Ω34\ \Omega34 Ω at S
81 exam-style questions on Edexcel GCSE Physics 10.2 Resistance, covering 10.2.1 Current in a circuit and conservation at junctions, 10.2.2 Resistance and variable resistors, 10.2.3 Series and parallel resistance, 10.2.4 I–V characteristics of components, and 10.2.5 LDRs and thermistors. Each one has a worked solution and a mark scheme showing where the marks go.