Question

An arc lamp consumes $10A$ at $40V$. If the power factor is $\frac{x}{10}$ when it is connected with a suitable value of choke coil required to run the arc lamp on ac mains of $200V$ (rms) and $50Hz$. Find $x$

Answer 1

$R=\frac{V}{I}=\frac{40}{10}=4\Omega$
$Z=\frac{V}{I}=\frac{200}{10}=20\Omega$
Power factor $\cos \varphi =\frac{R}{Z}=\frac{4}{20}$
$=0.2$