Question

Calculate the active power in a 9.854 H inductor.

(a) 4.98 W

(b) 0 W

(c) 8.59 W

(d) 1 W

I got this question in a job interview.

My doubt stems from Speed Control of Series Motor in chapter Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Correct option is (b) 0 W

To explain I would say: The inductor is a linear element. It only absorbs reactive power and stores it in the form of oscillating energy. The voltage and current are 90° in phase in case of the inductor so the angle between V & I is 90°. P=VIcos90° = 0 W.