Question

The potential differences across the resistance, capacitance and inductance are $80\, V$, $40\, V$ and $100\, V$ respectively in an $L-C-R$ circuit . The power factor of this circuit is

• A. 0.4
• B. 0.5
• C. 0.8
• D. 1

Answer 1

Answer: (C)

0.8

Answer 2

$\cos\phi = \frac{V_{R}}{V_{net}} = \frac{V_{R}}{\sqrt{\left(V_{L} - V_{C}\right)^{2} + V_{R^{2}}}}$
$= \frac{80}{ \sqrt{\left(100-40\right)^{2} + 80^{2}}} = \frac{80}{100} = 0.8$