Q.(a) Draw a labelled diagram of A.C. generator. [1]

An AC generator produces a sinusoidal emf as a coil rotates in a magnetic field; applying the ideal-transformer turns-ratio relations to the given step-down transformer gives the secondary current and power delivered.

1. Labelled diagram of an AC generator: An AC generator (alternator) consists of: a rectangular (or multi-turn) ARMATURE COIL free to rotate about an axis perpendicular to a uniform magnetic field $\vec{B}$ (produced by strong field magnets/poles, N and S); the two ends of the coil are connected to two SLIP RINGS, which rotate along with the coil; two fixed carbon BRUSHES press against the slip rings and connect the rotating coil to the external circuit; and a mechanical energy source (e.g. a turbine or hand crank) that rotates the coil/armature at constant angular speed $\omega$.
2. Expression for the instantaneous emf: As the coil (area $A$, $N$ turns) rotates with angular velocity $\omega$ in field $B$, the flux linked with it at time $t$ (measuring the angle from the position where the coil plane is perpendicular to $B$) is $\phi(t) = NBA\cos(\omega t)$ By Faraday's law, the induced emf is $e = -\dfrac{d\phi}{dt} = -NBA\dfrac{d}{dt}\cos(\omega t) = NBA\omega\sin(\omega t)$ Writing $e_0 = NBA\omega$ as the peak (maximum) emf: $e = e_0\sin(\omega t)$ This shows the emf varies sinusoidally with time, going through one full cycle each time the coil completes one rotation.
3. Step-down transformer: …