Question

The power factor of an ac circuit having resistance $R$ and inductance $L$ connected in series to an ac source of angular frequency $\omega$ is

• A. $\frac{R}{\omega L}$
• B. $\frac{\omega L}{R}$
• C. $\frac{R}{\sqrt{R^{2}+\omega^{2} L^{2}}}$
• D. zero

Answer 1

Answer: (C)

Power factor $=\cos \phi=\frac{R}{Z}$
$=\frac{R}{\sqrt{R^{2}+\omega^{2} L^{2}}}$