Question

The power factor of LCR circuit at resonance is(a) 0.707(b) 1(c) Zero(d) 0.5

Answer 1

answer : option (c)


explanation : we know, the formula,
$tan\phi=\frac{\omega L-\frac{1}{\omega C}}{R}$........(1)

at resonance,
inductive reactance = conductive reactance

e.g., $X_L=X_C$

or, $\omega L=\frac{1}{\omega C}$ .....(2)

from equations (1) and (2), it is clear that, $tan\phi$ = 0

so, $\phi=0^{\circ}$

now, power factor = $cos\phi$

= cos0° = 1

hence, power factor of LCR circuit at resonance is 1.