Q. 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
A) $2I_0$
B) $I_0$
C) $\frac{I_0}2$
D) $\frac{I_0}{\sqrt2}$
Explanation
[Solution by Dr. Abubacker] At resonance the impedance equals $R$, so $I_0=\frac ER$. With $2R$, the amplitude is $\frac E{2R}=\frac{I_0}2$. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.