Question 1

Paper 2Medium8 marks

A coil rotates at constant speed in a uniform magnetic field. The same coil and field are used for both rotations; only the rotational frequency changes. Figure 1 shows the induced emf for the two rotations.

00.10.20.30.40.5-16-12-8-40481216t / sε / VPQ
(a)

Determine the rotational frequency corresponding to each trace.

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(b)

Determine the ratio of the peak induced emf in Q to that in P. Using your answer to (a), deduce the relationship between peak induced emf and rotational frequency.

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(c)

Explain why increasing the rotational frequency increases the peak induced emf.

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(d)

Using the relationship inferred in (b), determine the peak induced emf when the same coil rotates at 3.0 Hz3.0\ \mathrm{Hz}

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