Given below are two statements: Statement I : When the frequency of an AC source in a series LCR circuit increases, the current in the circuit first increases, attains a maximum value and then decreases. Statement II : In a series LCR circuit, the value of power factor at resonance is one. In the…

Question

Given below are two statements: Statement I : When the frequency of an AC source in a series LCR circuit increases, the current in the circuit first increases, attains a maximum value and then decreases. Statement II : In a series LCR circuit, the value of power factor at resonance is one. In the light of given statements, choose the most appropriate answer from the options given below.

Aicharya · Accepted Answer

When an a.c. voltage is applied in a series LCR circuit, the current is increased first, attains a maximum and then decreases.

The formula to calculate the power factor is given by

$\cos ϕ = \frac{R}{\sqrt{R^{2} + ({X_{L}}^{2} - {X_{C}}^{2})}} . . . (1)$

At resonance, $X_{L} = X_{C}$ , Hence,

$\cos ϕ_{resonance} = 1$

Thus, both the statements are true.

Given below are two statements: Statement I : When the frequency of an AC source in a series LCR circuit…

Solution