Question

A LCR circuit is at resonance for a capacitor C, inductance L and resistance R. Now the value of resistance is halved keeping all other parameters same. The current amplitude at resonance will be now:

• A. Zero
• B. double
• C. same
• D. halved

Answer 1

Answer: (B)

double

Answer 2

At resonance, impedance is given by:

$Z = R.$

The current in the circuit is:
$I = \frac{V}{R}.$

When the resistance $R$ is halved:
$R \to \frac{R}{2}, \quad I \to 2I.$

Thus, the current amplitude becomes double.

Final Answer: Double.