An engineer measures the magnetic field around a long, straight conductor used to supply current to an electric railway. The table shows the magnetic flux density due to the current in the conductor.
| Current in A | Distance of sensor from conductor in cm | Magnetic flux density in μT |
|---|---|---|
| 80 | 4.0 | 400 |
| 160 | 4.0 | 800 |
| 80 | 8.0 | 200 |
Explain how the results show that the strength of the magnetic field depends on both the current and the distance from the conductor.
In another test, the current is initially 80 A and the sensor is 4.0 cm from the conductor. The current and the distance of the sensor from the conductor are both doubled.
Assume that the patterns shown in the table continue.
Predict the magnetic flux density measured by the sensor. Justify your answer.
90 exam-style questions on AQA GCSE Physics 7.2 The motor effect, covering 7.2.1 Electromagnetism, 7.2.2 Fleming's left-hand rule (HT only), 7.2.3 Electric motors (HT only), and 7.2.4 Loudspeakers (HT only). Each one has a worked solution and a mark scheme showing where the marks go.