$\phi = \pi r^2 B$
$ \frac {d\phi}{dt} = 2 \pi r . \frac {db}{dt}$
when $ r = 2 \times 10 ^{-2} m \;\; and\; \frac {dr}{dt} = 10 ^{-3} m/s$
$ e = \frac {d\phi}{dt} = 2 \times \frac {22}{7} \times (2 \times 10^{-2}) (0.02) \times 10^{-3}$
$ = 2.5 \times 10^{-6} V$
$ = 2.5 \mu V$