An engineer tests a vibration sensor. Inside the sensor, a rectangular coil can move up and down. Only the lower side of the coil is between the poles of a permanent magnet fixed to the sensor casing, and it stays between the poles as the coil moves. This side is horizontal and at right angles to the magnetic field lines, which are horizontal. A sensitive voltmeter measures the potential difference across the ends of the coil.
A positive velocity is upwards and a negative velocity is downwards.
| Velocity of coil relative to magnet in m/s | Voltmeter reading in V |
|---|---|
| +0.10 | +0.08 |
| +0.20 | +0.16 |
| 0.00 | 0.00 |
| -0.10 | -0.08 |
Explain why the voltmeter has a non-zero reading when the coil is moving but has a zero reading when the coil is momentarily stationary.
The coil then moves downwards at a velocity of 0.30 m/s. Use the data to calculate the voltmeter reading. Assume that the pattern shown by the data continues.
96 exam-style questions on AQA GCSE Physics 7.3 Induced potential, transformers and the National Grid (HT only), covering 7.3.1 Induced potential (HT only), 7.3.2 Uses of the generator effect (HT only), 7.3.3 Microphones (HT only), and 7.3.4 Transformers (HT only). Each one has a worked solution and a mark scheme showing where the marks go.