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TEST 1  Thursday Feb 14
at 8:109:30pm.
Rooms:
MDCL1110 MacID: abidishliz43
MDCL1309 MacID: loks2voloshg
MDCL1116 MacID: waldiedgzvulunm
Email me if you have a conflict !!!
Early test is at 5:306:50pm in REF102 (you must be on
the list to write it!)
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View Full Document RC Circuits
RC Circuits

circuits in which the currents vary in time

rate of charging a cap depends on C and R of circuit

differential equations
Discharging a Capacitor
Discharging a Capacitor
(

sign because q
decreases
for I > 0
That is, current in circuit equals the
decrease of charge on the capacitor)
C
R
q
q
I
Given:
R, C, q
o
(initial charge)
Find:
q(t)
and
I(t) when switch
is closed
dt
dq
I

=
2)
1)
0
=

IR
C
q
(Kirchhoff’s Loop Rule)
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View Full Document
R
q
q
I
RC
q
dt
dq

=
where:
q = q(t)
q(0) = q
o
This is a
differential equation
for the
function
q(t), subject
to the
initial condition
q(0) = q
0
.
We are looking for a function which is proportional to its own first
derivative (since dq/dt ~ q).
Combine 1) and 2) to get:
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This note was uploaded on 01/13/2011 for the course PHYSICS Physics 1E taught by Professor Venus during the Winter '03 term at McMaster University.
 Winter '03
 Venus
 Physics

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