In LCR series circuit if the frequency is increased, the impedance of the circuit (a) increases (b) decreases (c) either increases or decreases (d) first decreases then become minimum and then increases.

Answer: (d). Z = √(R² + (XL - XC)²) with XL ∝ f and XC ∝ 1/f. Z falls until XL = XC (resonance, Z = R), then rises as XL grows. So the answer is (d) first decreases, becomes minimum and then increases.

In LCR series circuit if the frequency is increased, the impedance of… | MHT CET 2024 (4 May, Shift 1)

Q46MHT CET 2024 · 4 MAY · SHIFT 1Easy

Resonance, Bandwidth & Q Factor

In LCR series circuit if the frequency is increased, the impedance of the circuit

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Answer: (d)

$Z = \sqrt{R^2 + (X_L - X_C)^2}$ with $X_L \propto f$ and $X_C \propto \dfrac{1}{f}$ .
$Z$ falls until $X_L = X_C$ (resonance, $Z = R$ ), then rises as $X_L$ grows.
So the answer is (d) first decreases, becomes minimum and then increases.

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