Slip of the induction machine is 0.02 and the stator supply frequency is 50 Hz.What will be the frequency of the rotor induced emf?

Slip of the induction machine is 0.02 and the stator supply frequency is 50 Hz.What will be the frequency of the rotor induced emf?

(A) 10 Hz. 
(B) 50 Hz.
(C) 1 Hz.
(D) 2500 Hz.

Explanatory answer:

S= 0.02 ; f = 50 Hz
Therefore, frequency of rotor induced emf = s f
                                                                         = 0.02 x 50 = 1 Hz