Download Electric Force - Parkland College

RC Circuits
We can use a resistor to slow the charging of the
capacitor.
C
Charge on capacitor varies
with time:
V
R
q = qo [1- e-t/RC]
-Current now varies with time.
-In the very short term, you can treat the capacitor like a wire.
R=0
-In the long term, you can treat the capacitor like a break.
R = Infinite
How much charge is on the capacitor after 1ms?
C= 10μF
V = 20V
R = 100Ω
How long does it take to gain 50% of maximum
Charge?
C= 10μF
V = 20V
R = 100Ω
How long does it take to gain 100% of maximum
Charge?
C= 10μF
V = 20V
R = 100Ω
We can use a resistor to slow the discharging of the
capacitor.
C (charged)
Charge on capacitor varies
with time:
R
q = qo [ e-t/RC]
-Current varies with time.
-The capacitor is now driving the current
-As the capacitor discharges, the voltage drops
- VC = VR
How much charge is left on the capacitor after 1ms?
C= 10μF
V = 20V
R = 100Ω
How long does it take to lose 70% of maximum
Charge?
C= 10μF
V = 20V
R = 100Ω
What is the current through the battery in very short term?
What is the current through the battery in the long term?
R1 = 5 Ω
V =20V
R2 = 10 Ω
C = 2μF
After a long time, what is the voltage drop across the Capacitor?
R1 = 5 Ω
V =20V
R2 = 10 Ω
C = 2μF