Question

How does total impedence of a series LCR circuit change if the frequency of the applied a.c. supply is increased and why?

Answer 1

Total impedance of the LCR circuit is given by :

Z = (R² + (X_{L -} X_C)² )^1/2
where R is the resistance
X_L = reactance offered by the inductor = $\omega L$
X_C = reactance offered by the capacitor = $1/\omega C$
L= inductance , C= capacitance

Z = (R² + ($\omega L$ - $1/\omega C$))^1/2
As frequency of the applied ac signal increase, ​$\omega L$ increases and $1/\omega C$ decreases.
Therefore, total impedance increases.