So if w is varied, then at a particular frequency
w0, Xc = XL, and the impedance is minimum (
)
2
02
Z
R
R
=
+
= This
frequency is called the resonant frequency:
0
0
1
or
c
L
X
X
L
C
ω
ω
=
=
or   
0
1
LC
ω
=
(7 28)
At resonant frequency, the current amplitude
is maximum; im = vm/R Figure 7