Question

In L-C-R circuit power factor at resonance is

• A. Less than one
• B. Greater than one
• C. Unity
• D. Can't predicted

Answer 1

The correct option is C Unity

$\tan \varphi =\frac{\omega L-\frac{1}{\omega C}}{R}$

At resonance, $X_L=X_C$. Thus the net voltage, current and voltage across the resistor are all in phase. Hence the phase angle $\varphi =0$

Thus the power factor becomes $cos\varphi =1$