Question

The equation of instantaneous power is?

(a) P (t) = (VmIm/2)(cos⁡(2ωt+θ)+sin⁡θ)

(b) P (t) = (VmIm/2)(sin⁡(2ωt+θ)+cos⁡θ)

(c) P (t) = (VmIm/2)(cos⁡(2ωt+θ)+cos⁡θ)

(d) P (t) = (VmIm/2)(sin⁡(2ωt+θ)+sin⁡θ)

The question was posed to me in an online interview.

This interesting question is from Instantaneous Power topic in chapter Power and Power Factor of Network Theory

Answer 1

Right option is (c) P (t) = (VmIm/2)(cos⁡(2ωt+θ)+cos⁡θ)

To elaborate: The equation of instantaneous power is P (t) = (VmIm/2)(cos⁡(2ωt+θ)+cos⁡θ). It consists of two parts. One is a fixed part and the other is time varying which has frequency twice that of the voltage or current wave forms.