Question

For given circuit the power factor is :-

• A. $0$
• B. $\frac{1}{2}$
• C. $\frac{1}{\sqrt{2}}$
• D. none of these

Answer 1

The correct option is C $\frac{1}{\sqrt{2}}$

Power factor $=\cos \varphi$

where, $\varphi =$ Phase angle

Suppose $i$ is flowing in the circuit.

$X_L=$ Inductive reactance.

$X_L=2\pi fL=2\pi \times 50\times 3.5=350\pi$

$P.F=\cos \varphi =\frac{R}{\sqrt{R^2+X_L^2}}=\frac{1100}{\sqrt{{1100}^2+(350\pi {)}^2}}=\frac{100}{\sqrt{{1100}^2+{1100}^2}}=\frac{1}{\sqrt{2}}$