The heater in a weather sensor contains two of the four heating elements listed in the table, connected in series. The elements are sealed inside the sensor, so a maintenance technician identifies them from meter readings.
| Heating element | Resistance |
|---|---|
| W | 6.0 Ω |
| X | 12 Ω |
| Y | 18 Ω |
| Z | 24 Ω |
With the heater connected to a 12 V supply, the ammeter reads 0.40 A. A voltmeter connected across one of the elements reads 7.2 V. Which two elements are fitted, and which element has the voltmeter across it?
X and Y, with the voltmeter connected across X
W and Y, with the voltmeter connected across Y
W and Z, with the voltmeter connected across Z
X and Y, with the voltmeter connected across 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.