Question

In a DC series motor, the e.m.f developed is proportional to _______

(a) N×Ia

(b) N×Ia^2

(c) N×Ia^3

(d) N×Ia^.5

I got this question in unit test.

The question is from Induction Motors in chapter Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Correct option is (a) N×Ia

The best explanation: In a DC series motor, the e.m.f developed is equal to KmΦN. In a DC series, the motor field winding is connected in series with the armature so the flux in the field winding is proportional to current. Eb = KmΦN α Ia×N.