
150 Network Analysis and Synthesis
At resonant frequency f
r
, X
L
= X
C
, Z = R (minimum), and hence, the current is maximum.
The voltage across the capacitor and the inductor can be much larger than the supply voltage but
these two voltages oppose each other making their combined voltage as zero.
Resonance Condition
The variations of I, V
R
, V
L
, V
C
and V
CL
with variation of frequency in the series R–L–C circuit
have been shown in Figure 4.3. At resonance frequency f
r
, the impedance of the circuit is R only,
and hence, the maximum current flows in the circuit creating a resonance condition.
Under the resonance condition, the impedance of the circuit ...