Question

Calculate the active power in an 8965 Ω resistor with .23 A current flowing through it.

(a) 547.12 W

(b) 474.24 W

(c) 554.78 W

(d) 123.88 W

This question was posed to me in a job interview.

The doubt is from Methods to Reduce the Energy Loss During Starting topic in section Starting of Electric Drives

Answer 1

Right option is (b) 474.24 W

To explain: The resistor is a linear element. It only absorbs real power and dissipates it in the form of heat. The voltage and current are in the same phase in case of the resistor so the angle between V & I is 0°. P=I^2R=.23×.23×8965=474.24 W.