First slide

AC Circuits

Question

Which one of the following curves represents the variation of impedance (Z) with frequency f in series LCR circuit

Moderate

A
B
C
D

Solution

$Z = \sqrt{R^{2} + {(2 πfL - \frac{1}{2 πfC})}^{2}}$
From above equation at f = 0 $\Rightarrow z = \infty$
When $f = \frac{1}{2 π \sqrt{LC}}$ (resonant frequency) $\Rightarrow Z = R$
For $f > \frac{1}{2 π \sqrt{LC}} \Rightarrow$ Z starts increasing.
i.e., for frequency 0 – f_r, Z decreases
and for f_r to $\infty$ , Z increases. This is justified by graph 3.

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App