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Q.
An alternating voltage $e =200 \sin 100 t$ is applied to a series combination of $R =30 \Omega$ and an inductor of 400 $mH$. The power factor of the circuit is:
Alternating Current
Solution:
Power factor $\cos \phi=\frac{ R }{ Z }$
$Z=\sqrt{R^{2}+X_{L}^{2}}=\sqrt{R^{2}+(\omega L)^{2}}$
$Z=\sqrt{(30)^{2}+\left(100 \times 400 \times 10^{-3}\right)^{2}}=\sqrt{900+1600}=\sqrt{2500}$
$Z=50 \Omega$
$\therefore \cos \phi=\frac{R}{Z}=\frac{30}{50}=0.6$