The plane of a coil of area $100 {\mathrm{m}}^2$ is at right angles to a magnetic field of induction ${10}^{-2} \mathrm{Wb} {\mathrm{m}}^{-2}$. If the field decreases to $5\times {10}^{-3}$ $\mathrm{Wb} {\mathrm{m}}^{-2}$ in $5 \mathrm{s}$, find the average induced emf in the coil.

A long solenoid having $220 \mathrm{turns} \mathrm{per} \mathrm{cm}$ , carries a current of $1.5 \mathrm{A}$, its diameter being $3.2 \mathrm{cm}$. Another close$‐$packed coil $C$ of $130 \mathrm{turns}$ and diameter $2.1 \mathrm{cm}$ lies co$‐$axially at the centre of the solenoid. Find the emf induced $($in $\mathrm{mV})$ in $C$ when the current in the solenoid is reduced to zero at a steady rate in $25 \mathrm{ms}$.

(Answer to the nearest integer)