Physics 5054 · O Level · The a.c. generator

The a.c. generator — practice question

An a.c. generator is installed in a remote area to provide electricity. Fig. 7.1 illustrates the layout of a simple a.c. generator with the coil drawn horizontally. The diagram labels the output terminals, P, Q, N, S, the horizontal coil and the direction of rotation.
(a(i))[1]

State the names of the components labelled P and Q in Fig. 7.1.

(a(ii))[2]

When the generator is delivering electrical output, P remains still and Q turns. Explain the purpose of P and Q.

(b(i))[1]

Write a letter X on the trace shown in Fig. 7.2 to show one instant when the coil is vertical.

(b(ii))[2]

Using Fig. 7.2, determine the maximum value of the e.m.f. produced by the generator.

(b(iii))[1]

Using Fig. 7.2, determine, in milliseconds, how long one revolution of the coil takes.

(b(iv))[2]

Determine the frequency of the output of the generator.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: P: carbon brush; Q: slip rings

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