This preview shows page 1. Sign up to view the full content.
8.
A series RLC circuit has R = 1.200Ω, L = 220.0mH, C = 12.00μF. What fraction of its
original maximum charge does the capacitor attain after one cycle?
(1) 0.9725
(2) 0.9925
(3) 0.9825
(4) 0.9625
(5) 0.9993
In RLC circuits, the capacitor equation for charge becomes
( 29
2
cos
Rt
L
q
Qe
t
ϖ
φ

=
+
The most troublesome thing about this equation is the
( 29
cos
t
+
. Fortunately, we
know that the maximum charge would come when
( 29
cos
1
t
+
=
. And after a
“complete cycle” of the wave, we know that the cosine would return to its original
value, which is also 1. Thus, the equation reduces to
2
Rt
L
q
Qe

=
A “cycle” represents the time. It can be found from the equation for natural frequency,
This is the end of the preview. Sign up
to
access the rest of the document.
 Spring '08
 Any
 Physics, Charge

Click to edit the document details