A ring rotates with angular velocity `omega` about an axis in the plane of the ring which passes through the center of the ring. A constant magnetic field `B` exists perpendicualr to the plane of the ring . Find the emf induced in the ring as a function of time.

Explanation

At any time `t`, `phi = BA cos theta = BA cos omegat`
Now, induced emf in the loop
`e = -(dphi)/(dt) = BA` omega sin omegat
If there are `n` turns,
`emf = BA omegaN sin omegat`
`BA omegaN` is the amplitude of the emf `e = e_(m)` sin omegat, where `e_(m) = BA omega N`
`i = (e)/(R) = (e_(m))/(R) sin omegat = i_(m) sin omegat`
where `i_(m) = (e_(m))/(R)`.
the rotating coil thus produces a sinusoidally varying current or alternating current. This is also the principle used in generator.