Question

A series LCR circuit is connected to an alternating source of emf E. The current amplitude at resonant frequency is \(I_0\) . If the value of resistance R becomes twice of its initial value then amplitude of current at resonance will be

(1) \(I_{0}\)

(2) \(\frac{I_{0}}{2}\)

(3) \(\frac{I_{0}}{\sqrt{2}}\)

(4) \(2 \mathrm{I}_{0}\)

Answer 1

Correct option is : (2) \(\frac{I_{0}}{2}\) 

Initially, \(\mathrm{I}_{0}=\frac{\varepsilon_{\mathrm{m}}}{\mathrm{R}}\)

Finally, \(I_{0}^{1}=\frac{\varepsilon_{m}}{2 R}=\frac{I_{0}}{2}\)