A 500-turn circular coil with an area of 0.500 m^2 is mounted on a rotating frame which turns at a rate of 20.0 rad/s in the presence of a 0.500 T uniform magnetic field that is perpendicular to the axis of rotation. What is the instantaneous emf in the coil at the moment that the perpendicular to its plane is at a 90.0 degree angle to the field?