Q.An ac generator converts

An AC generator converts mechanical rotation into electrical energy by rotating a coil (the armature) with N turns and area A at constant angular velocity $\omega$ within a uniform magnetic field B. As the angle $\theta=\omega t$ between the field and the coil's area vector changes, the linked flux $\Phi_B=BA\cos\omega t$ changes, inducing (by Faraday's law) an emf $e=NBA\omega\sin\omega t=e_0\sin\omega t$, where $e_0=NBA\omega$ is the peak emf -- a smoothly alternating (sinusoidal) output, since the emf is maximum when the coil's plane is parallel to B (conductors cutting field lines fastest) and zero when the coil's plane is perpendicular to B (conductors moving parallel to the field lines). …