(a) Principle of ac generator: Working of ac generator is based on the phenomenon of electromagnetic induction. whenever magnetic flux linked with a coil changes, an emf is induced in the coil. The direction of current induced is given by flemming's right hand rule.
(b)
Magnitude of emf generated in the coil:
Suppose at any instant of time 't', normal to the coil makes an angle θ with the direction of \(\overset{\rightarrow}{B}\)(magnetic field), as shown:
Let, N: number of turns in the coil,
A : area enclosed by coil
\(\therefore\) Magnetic flux, \(\phi\) = \(N(\overset{\rightarrow}{B}.\overset{\rightarrow}{A})\)
= NBA cosθ
= NBA cosωt; ω:- angular velocity of the coil
\(\therefore\) emf induced, e = -\(\frac{d\phi}{dt}\) = -\(\frac{d}{dt}\)(NBA cosωt)
= -NBA \(\frac{d}{dt}\)(cosωt)
= -NBA.(-sinωt).ω
∴ e = NBAω sinωt
(c) Yes, it is possible to generate emf without rotating the coil. Instead of rotation, if coil is allowed to move with velocity \(\perp_r\) to field, then also motional emf is induced. Also, by changing A and B, emf is induced.
