Question

Calculate the power factor if the power angle is 45°.

(a) .707

(b) .407

(c) .608

(d) 1

This question was posed to me in class test.

This interesting question is from Induction Motors in chapter Speed Control of Direct Current Motors & Induction Motors of Electric Drives

Answer 1

The correct option is (a) .707

To explain I would say: Power factor is the ratio of the real power to the apparent power. It measures the useful power contained in the total power cosΦ=cos(45°)=.707.