What is the coil pitch to eliminate the 5^th harmonic in the induced e.m.f. of a synchronous generator?

Concept:

Pitch factor(k_p) - it is the ratio of EMF induced in the short pitch coil to the full pitch coil.

it is given by , k_p =  ;

here 'n' represents the n^th order harmonics

Calculation:

To eliminate the nth order harmonics the pitch factor must be equated to 0

⇒ kp =  = 0

According to the question we have to eliminate the 5^th harmonic 

⇒  = , here n = 5

⇒ α = 36°

Therefore the coil should be pitched at  α = 36 to eliminate the 5th order harmonic in the induced e.m.f. of a synchronous generator.

Hence the correct option is 1.