Question

The inductance of a choke coil is $0.1\, H$ and resistance is $12 \,\Omega .$ If it is connected to an alternating current source of frequency $60 \,Hz$, then power factor will be

• A. 0.32
• B. 0.30
• C. 0.28
• D. 0.24

Answer 1

Answer: (B)

$\cos \phi=\frac{R}{Z}=\frac{R}{\sqrt{R^{2}+\omega^{2} L^{2}}}$
$=\frac{12}{\sqrt{(12)^{2}+4 \times \pi^{2} \times(60)^{2} \times(0.1)^{2}}}$
$ \Rightarrow \cos \phi=0.30$