Magnetic field, \(B=0.025\, \mathrm{T}\)

Radius of the loop, \(r=2 \,\mathrm{cm}=2 \times 10^{-2} \,\mathrm{m}\)

Constant rate at which radius of the loop shrinks,

\(\frac{d r}{d t}=1 \times 10^{-3}\, \mathrm{ms}^{-1}\)

Magnetic flux linked with the loop is

\(\phi=B A \cos \theta=B\left(\pi r^{2}\right) \cos 0^{\circ}=B \pi r^{2}\)

The magnitude of the induced \(emf\) is

\(|\varepsilon| =\frac{d \phi}{d t}=\frac{d}{d t}\left(B \pi r^{2}\right)=B \pi 2 r \frac{d r}{d t} \)

\(=0.025 \times \pi \times 2 \times 2 \times 10^{-2} \times 1 \times 10^{-3} \)

\(=\pi \times 10^{-6} \,\mathrm{V}=\pi \,\mu \mathrm{V}\)