Electromagnetic Induction

A conducting circular loop is placed in a uniform magnetic field of \(0.4 \mathrm{~T}\) with its plane perpendicular to the field. Somehow, the radius of the loop starts expanding at a constant rate of \(1 \mathrm{~mm} / \mathrm{s}\). The magnitude of induced emf in the loop at an instant when the radius of the loop is \(2 \mathrm{~cm}\) will be ___________ \(\mu \mathrm{V}\).