Question

An alternating current of $4\text{A},50\text{Hz}$ flows through a coil. The average power consumed in the coil is $240\text{W}$. If the rms voltage of the source is $100\text{V}$, the power factor is

• A. $\frac{1}{5}$
• B. $\frac{3}{5}$
• C. $\frac{2}{5}$
• D. $\frac{4}{5}$

Answer 1

The correct option is B $\frac{3}{5}$

We know that, average power consumed,

$P_{\text{avg}}=E_{\text{rms}}{i}_{\text{rms}}\cos \varphi$

$\Rightarrow 240=100\times 4\times \cos \varphi$

$\Rightarrow \cos \varphi =\frac{3}{5}$

Hence, option $\left(B\right)$ is the correct answer.