A circular coil with a radius a, resistance R, and self-inductance L has N turns. The coil is put in a uniform magnetic field B, and rotates around an axis which is normal to B. When the coil rotates around the axis with a constant angular velocity w. Find (a) the current induced in the coil as a function of the angle 0, where 0(t) = at is the included angle between the normal direction of the coil surface i and the magnetic field B. (b) in order to maintain the rotation of the coil with the angular velocity, what is the magnitude of external torque exerted on it? op B

A circular coil with a radius a, resistance R, and self-inductance L has N turns. The coil is put in a uniform magnetic field B, and rotates around an axis which is normal to B. When the coil rotates around the axis with a constant angular velocity w. Find (a) the current induced in the coil as a function of the angle 0, where 0(t) = at is the included angle between the normal direction of the coil surface i and the magnetic field B. (b) in order to maintain the rotation of the coil with the angular velocity, what is the magnitude of external torque exerted on it? op B