A certain elastic conducting material is stretched into a circular loop. It is placed with its plane perpendicular to a uniform magnetic field \( B = 0.8 \, \text{T} \). When released the radius of the loop starts shrinking at a constant rate of \( 2 \, \text{cm s}^{-1} \). The induced emf in the loop at an instant when the radius of the loop is \( 10 \, \text{cm} \) will be ______ \( \text{mV} \).
