Question

A certain series resonant circuit has a bandwidth of $2\text{kHz}$. If the existing coil is replaced with one having a higher value of $Q$ factor, the bandwidth will

• A. Increase
• B. Decrease
• C. Remain the same
• D. Be less selective

Answer 1

The correct option is B Decrease

We know that, the quality factor is given by,

$Q=\frac{{\omega }_0}{2\Delta \omega }$

Here, ${\omega }_0$ is the resonance frequency.

$2\Delta \omega$ is the bandwidth.

$\Rightarrow 2\Delta \omega =\frac{{\omega }_0}{Q}$

Therefore, from the above formula we can say that as quality factor increases, bandwidth decreases.

Hence, $\left(B\right)$ is the correct answer.