Given below are two statements:
Statement I: Maximum power is dissipated in a series LCR circuit connected to an AC source when resonance occurs.
Statement II: Maximum power is dissipated in a pure resistor because the phase difference between current and voltage is zero. Choose the correct answer.

Question

Given below are two statements:

Statement I: Maximum power is dissipated in a series LCR circuit connected to an AC source when resonance occurs.

Statement II: Maximum power is dissipated in a pure resistor because the phase difference between current and voltage is zero. Choose the correct answer.

G1 Physics · Accepted Answer

For a series LCR circuit, Z = √[R² + (X(L) - X(C))²] At resonance, X(L) = X(C) Therefore, Z = R The impedance is minimum, current is maximum, and current is in phase with voltage. Hence average power P = V(rms)I(rms)cosφ is maximum. For a pure resistor, φ = 0 and cosφ = 1, so the power factor is maximum. Therefore both statements are true. Option D follows.