Q. The coefficient of induction of a choke coil is $0.1H$ 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
Explanation
(b) $\cos\phi = \frac{R}{Z} = \frac{R}{\sqrt{R^{2} + \omega^{2}L^{2}}}$
$= \frac{12}{\sqrt{(12)^{2} + 4 \times \pi^{2} \times (60)^{2} \times (0.1)^{2}}} \Rightarrow \cos\phi = 0.30$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.