The service record for a fixed resistor in an automatic parcel-weighing machine states that the potential difference across it was 3.6 V when the current through it was 120 mA.
A technician tests four possible replacements.
| Replacement | Potential difference / V\mathrm{V}V | Current / mA\mathrm{mA}mA |
|---|---|---|
| W | 2.4 | 80 |
| X | 2.4 | 180 |
| Y | 3.6 | 30 |
| Z | 4.8 | 120 |
Which replacement should the technician choose so that the resistance is unchanged?
replacement X
replacement W
replacement Z
replacement Y
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.