- #1
sweetdion
- 64
- 0
Homework Statement
For the circuit shown below, the capacitors are initially uncharged. At t=0, the switch S is closed.
a) Determine the current in each resistor immediately after the switch is closed.
b) Determine the current in each resistor a very long time after the switch is closed.
c) Determine the voltage across the capacitor a very long time after the switch is closed.
After the switch has been closed for a very long time, it is reopened.
d) Determine the initial current I0 through the 100 ohm resistor, as a function of time after the switch is reopened.
e) Determine I(t), the current through the 100 ohm resistor, as a function of time after the switch is reopened.
f) How long after the switch is reopened does the charge on the capacitor fall to 10% of its fully charged state?
Homework Equations
V=IR
I through a capacitor is I = Cdv/dt = Q/C
Kirchoff's Loops Rules
The Attempt at a Solution
a) Immediately after the switch is closed, the capacitor behaves ls a short circuit and hence no current flows through the 100 ohm resistor.
I in the 200 ohm resistor = V/R=15V/200ohms=.075A
b) long after the switch is closed, the capacitor is fully charged and behanves as an open circuit. All of the current passes through both resistors.
Left Loop Clockwise:
15V-200ΩI1-100ΩI1=0
Right Loop Counter clockwise: Q/C-100ΩI1-0
I1 is the only current passing through both the resistors
I= 20A
as for the rest of the parts, I want to make sure I get A and B right before I move on.