Report for Experiment #18
RC Circuits
Madeline Gershman
Lab Partner: Daniel Potapov
TA: Rebecca Harman
February 19th, 2019
Abstract
In this lab, the charging and discharging of a capacitor is analyzed in an RC cir
...
Report for Experiment #18
RC Circuits
Madeline Gershman
Lab Partner: Daniel Potapov
TA: Rebecca Harman
February 19th, 2019
Abstract
In this lab, the charging and discharging of a capacitor is analyzed in an RC circuit; the capacitor is
analyzed in circuits in parallel and series. The first investigation studies the charging of a capacitor; the
time constant was derived to be 125 seconds. The second investigation studies the discharging of
capacitors; the time constant was derived to be133.3 seconds. The third investigation studies the
differences in capacitors between parallel and series circuits. The parallel circuit found a time constant of
125 seconds.Introduction
When capacitors are added to resistor circuits, they change the voltage and current of the circuit as
time passes. Capacitors act as storage containers for charge; as time passes, the capacitor stores more and
more charge, which in turn alters the circuit attached to it. The charge is found using
Q=CV
The C in this equation represents the capacitance, or how much charge a capacitor can hold at a certain
voltage. Depending on the configuration of the circuit, parallel or series, capacitors can act different.
When the circuit is closed, the capacitor begins to collect charge as current flows through; once a resistor
is connected across the terminal, the capacitor will begin to discharge. The rate at which this charge
accumulates because of the current can be represented by
I=dQ
dt =C dV dT
As the name indicates, RC circuits include both capacitors and resistors, as well as a power source and a
switch; this relationship between the components of an RC circuit can be represented by Kirchhoff’s loop
rule
Q (t)=Cε(1−e
−t
RC)
The derivative of this equation helps us to determine the current flowing through the circuit,
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