An engineer is designing an electromagnetic catch that holds an iron plate in place.
The engineer tests five coil designs. The maximum pulling force is the force needed to separate the iron plate from the coil.
| Design | Number of turns | Core material | Current in coil / A | Maximum pulling force / N |
|---|---|---|---|---|
| A | 120 | plastic | 0.80 | 0.9 |
| B | 120 | iron | 0.80 | 7.2 |
| C | 240 | iron | 0.80 | 14.0 |
| D | 240 | iron | 0.40 | 7.1 |
| E | 360 | iron | 0.40 | 10.5 |
Describe what the results show about how the core material and the number of turns affect the strength of the coil. Use data from the table.
The catch must provide a pulling force of at least 10.0 N without the current exceeding 0.40 A.
Give the design that should be used and one reason for 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.