Question

The power factor of a.c. circuit having L and R connected in series to an a.c. source of angular frequency $\omega$ is given by :

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

Answer 1

Answer: (B)

$\frac{R}{\sqrt{R^2+{\omega }^2{L}^2}}$

Power factor $=\frac{R}{Z}$

$=\frac{R}{\sqrt{R^2+w^2{L}^2}}$