(a)[3]
State the meaning of the magnetic flux linkage of a coil.
(b)[2]
A wire coil contains $160$ turns and has a diameter of $2.4\,\text{cm}$. The coil lies in a uniform magnetic field with flux density $7.5\,\text{mT}$, as shown in Fig. 9.1. The magnetic field is directed along the coil axis. The flux density is brought down to zero over $0.15\,\text{s}$. Show that the average e.m.f. induced in the coil is $3.6\,\text{mV$.
(c)[4]
The magnetic flux density $B$ in the coil in (b) is now changed with time $t$ as shown in Fig. 9.2. Use the data in (b) to show, on Fig. 9.3, how the e.m.f. $E$ induced in the coil varies with time $t$.