Q70 / 90 · JEE Main 2021 (31 Aug Shift 1) · Physics

In an ac circuit, an inductor, a capacitor and a resistor are connected in series with $X_{L} = R = X_{C} .$ Impedance of this circuit is :

A
Zero
Correct answer
B
$R$
C
$R \sqrt{2}$
D
$2 R^{2}$

Solution

Recall the formula of impedance is in terms of resistance,

Z = \sqrt{{(X_{L} - X_{C})}^{2} + R^{2}}

, here, the condition of resonance,

X_{L} = X_{C}

, it means,

Z = \sqrt{{(X_{L} - X_{L})}^{2} + R^{2}} = R

Hence, the correct answer is option: 'B'.

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