19. •• An ac generator operates at a rotational frequency of 60 Hz and produces a maximum emf of 100 V.

Assume that its output at t = 0 is zero. What is the instantaneous emf

(a) at t = 1/240 s?

(b) at t = 1/120 s?

(c) Find an expression for the instantaneous emf at any time t.

(d) How much time elapses between successive 0-volt outputs?

(e) What maximum emf would this generator produce if it were operated instead at 120 Hz?