Question

Calculate the active power in an 8.12 F capacitor.

(a) 89 W

(b) 41 W

(c) 0 W

(d) 48 W

I had been asked this question in an internship interview.

This is a very interesting question from Induction Motors topic in section Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Correct choice is (c) 0 W

The best I can explain: The capacitor 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 capacitor so the angle between V & I is 90°. P=VIcos90° = 0 W.