Page 146 - The Master Handbook Of Acoustics

121
ANALOG AND DIGITAL SIGNAL PROCESSING

effect of a capacitance. Figure 6-2 shows
the symbols for inductance (L), commonly L
a coil of wire, and capacitance (C), com-
monly made of sheets of conducting mate-
rial separated by nonconducting sheets.
Energy can be stored in the magnetic field
of an inductance as well as in the electrical
charges on the plates of a capacitance. The
interchange of energy between two such C
storage systems can result in a resonance
effect. Perhaps, the simplest example of
this is a weight on a spring.
Figure 6-3 shows two forms in which
an inductance and a capacitance can
exhibit resonance. Let us assume that an FIGURE 6-2
alternating current of constant amplitude,
Symbols for inductance (L) and capitance (C).
but varying frequency is flowing in the
parallel resonant circuit of Fig. 6-3A. As

V V

L Generator
C
L
C

Voltage Voltage

Freq. Freq.
A B

FIGURE 6-3
A comparison of (A) parallel resonance and (B) series resonance. For a constant alter-
nating current flowing, the voltage across the parallel resonant circuit peaks at the res-
onance frequency while that of the series resonant circuit is a minimum.