When a conducting disc or wheel of radius r rotates with constant angular velocity of ω about its axis in a uniform magnetic field perpendicular to its plane and parallel to its axis of rotation, then, 
Induced emf is given by, e=21 Bωr22 Here, B=0.1 T,ω=10rad/s,r=0.5 m Substituting these values in Eq. (i), we get ∴e=21×0.1×10×(0.5)2=81 V=0.125 V