Question Constellation Sign up for free AQA · GCSE · Physics · Higher
Inducing Current with a Moving Wire
Figure 13 shows a wire held between two magnets. The wire forms part of a closed circuit connected to an ammeter.
The teacher moved the wire upwards between the magnets. The needle on the ammeter deflected to a value of +0.4 mA and then returned to zero.
Explain why a current was detected when the wire in Figure 13 was moved upwards.
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Marking points
- 1 States that the moving wire cuts through the magnetic field.
- 2 States that a potential difference is induced across the wire.
- 3 Links the complete circuit to the detected current.
Full-mark answer
As the wire moved upwards it cut through the magnetic field between the magnets, so a potential difference was induced across the wire. The wire was part of a complete circuit, so the induced potential difference caused a current in the circuit.
Why this answer loses marks
The magnets push current through the wire.
The explanation must link the moving wire cutting the field to an induced potential difference, then use the complete circuit to explain current.