Charge on capacitor (RC circuit)

[cashmoney805]

Homework Statement

1) Determine the current in each resistor and charge on the capacitor after a long time immediately after the switch is closed
2) Determine the current in each resistor and charge on the capacitor after a long time

After the switch has been closed for a long time it is re-opened.

3) Determine the current in each resistor and the charge on the capacitor immediately after the switch has been re-opened.
4) Determine the time constant of the capacitor discharge.

Homework Equations

V = I Req
Q = CV

The Attempt at a Solution

I got #1 and got I6 = 1A, I8 = 1.5A, and I12 = .5A
I'm not sure what to do about #2 though. What is the voltage across the capacitor? I thought it would be 6V, because that is the voltage across the parallel series. However, there is a voltage drop after the 1A current runs across the 6ohm resistor so the V across the capacitor is 0.

For #3 and 4, does the 8ohm resistor come into play or no?
Thanks for the help guys.

 

[cashmoney805]

Is the V across the capacitor just 6V? If so I think I'm good. #2 I through the 6ohm resistor is 0, then I through the other two resistors is 18V/20ohms right?
#3 I = 6V/18ohms Q= 28 E-6 * 6
#4 (18 * 28E-6) = RC

 

[rl.bhat]

Voltage which charges the capacitor is the voltage across 12 ohm resistance. Calculate that voltage.
When the capacitor is completely charged, the same voltage will be the voltage across it.

 

[cashmoney805]

oh is this Kirchoff's rule?

 

[rl.bhat]

No. There is no need to apply Kirchhoff rule.