Question

At resonant frequency (${\omega }_0$) of an LCR series circuit, impedance of circuit is $Z$. At ${\omega }_0+\Delta \omega$, impedance is Z', and at ${\omega }_0-\Delta \omega$ impedance is Z", then (where $\Delta \omega =\frac{1}{2}$ Bandwidth)

• A. Z' = Z" > Z
• B. Z > Z' > Z"
• C. Z > Z' = Z"
• D. Z < Z' < Z"

Answer 1

The correct option is C Z > Z' = Z"

At ${\omega }_0$, impedance is maximum.

At ${\omega }_0+\Delta \omega$ and ${\omega }_0-\Delta \omega$ the impedances and current are same.
Z" = Z' < Z