Fig. 6.1 shows a basic a.c. generator. The diagram labels are: coil, N pole, S pole, rotation of coil, and output voltage. Fig. 6.2 shows how the alternating e.m.f. varies with time.
(a(i))[2]
Explain why an e.m.f. is produced.
(a(ii))[1]
Explain why the e.m.f. sometimes has a positive value and sometimes a negative value.
(b)[3]
The a.c. generator is altered in three separate ways, one at a time: stronger magnets are fitted; extra turns are wound on the coil; the coil is rotated more quickly. Fill in Fig. 6.3 to show what happens to the maximum e.m.f. value and to the frequency of the alternating e.m.f.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Magnetic flux through the coil changes” …