The low-frequency circuit impedance and the high-frequency circui
A. capacitive and inductive
B. inductive and capacitive
C. resistive and inductive
D. capacitive and resistive
Please scroll down to see the correct answer and solution guide.
Right Answer is: A
SOLUTION
In a series RLC circuit, the impedance is given by
\(Z = \sqrt {{R^2} + {{\left( {{X_L} - {X_C}} \right)}^2}} \)
Where R is the resistance
XL is the inductive reactance
XC is the capacitive reactance
Current (I) = V/Z
Impedance Vs frequency in a RLC series circuit:
\(Z = \sqrt {{R^2} + {{\left( {{X_L} - {X_C}} \right)}^2}} \)
\( = \sqrt {{R^2} + {{\left( {\omega L - \frac{1}{{\omega C}}} \right)}^2}} \)
At ω = 0, Z = infinity and the impedance is capacitive
At ω = ω0, i.e. at the resonant frequency, the inductive reactance is equal to the capacitive reactance. At this condition, impedance is purely resistive, and it is equal to R. The impedance is maximum in this case.
At ω = ∞, Z = infinity and the impedance is inductive.
