(a)
Fig. $9.2$ shows how $B$ varies with time $t$.
(a(i))[2]
Demonstrate that the electromotive force (e.m.f.) induced in the coil from $t = 0$ to $t = 0.20\,\text{s}$ is $0.080\,\text{V}$.
(a(ii))[4]
Using the axes in Fig. $9.3$, plot how the induced e.m.f. $E$ changes with time $t$ from $t = 0$ to $t = 0.80\,\text{s}$.
(b)[4]
A bar magnet is supported by a rod a short distance above an aluminium disc, as shown in Fig. $9.4$. The aluminium disc is mounted horizontally and remains at rest. The magnet is turned about a vertical axis at constant speed. Using laws of electromagnetic induction, explain why a torque acts on the aluminium disc.