Question

Calculate the active power in a 1.7 Ω resistor with 1.8 A current flowing through it.

(a) 5.5 W

(b) 5.1 W

(c) 5.4 W

(d) 5.7 W

I got this question by my college professor while I was bunking the class.

Query is from Induction Motors topic in portion Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

Right choice is (a) 5.5 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=1.8×1.8×1.7=5.5 W.