A technician checks a fixed resistor used in a greenhouse ventilation controller. The ammeter has the same zero error throughout the check. Its readings are shown below.
| Test condition | Potential difference across resistor / V\mathrm{V}V | Ammeter reading / A\mathrm{A}A |
|---|---|---|
| No current flowing | 0.0 | -0.03 |
| Controller operating | 8.1 | 0.27 |
What is the resistance of the resistor after correcting for the ammeter's zero error?
33.8 Ω33.8\ \Omega33.8 Ω
27.0 Ω27.0\ \Omega27.0 Ω
270 Ω270\ \Omega270 Ω
30.0 Ω30.0\ \Omega30.0 Ω
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.