Question

If the phase difference between alternating current and e.m.f is \(\phi\), then the value of power factor is:

• A. \( \cos \phi \)
• B. \( \sin \phi \)
• C. \( \tan \phi \)
• D. None of these

Hint:

Power factor determines how effectively the circuit converts electric power into useful work.

Answer 1

The Correct Option is A

In an alternating current (AC) circuit, the power factor is defined as the cosine of the phase difference \( \phi \) between the voltage (electromotive force) and the current. It represents the fraction of the total power that is effectively used to do useful work. Mathematically, \[ \text{Power factor} = \cos \phi, \] where \( \phi \) is the angle by which the current either leads or lags the voltage. A power factor of 1 indicates that voltage and current are in phase, and all the power is effectively utilized, whereas a lower power factor indicates the presence of reactive components causing energy to oscillate back and forth without being consumed.