What is the final charge and potential difference on each capacitor?

[ooohffff]

Homework Statement

In the circuit shown in the figure, C1 = 1.0 µF, C2 = 1.9 µF, C3 = 2.8 µF, and a voltage Vab = 30 V is applied across points a and b. After C1 is fully charged the switch is thrown to the right. What is the final charge and potential difference on each capacitor?

Homework Equations

Q=CV

The Attempt at a Solution

I found everything (V₁, Q₂, V₂, Q₃, V₃) except for Q₁. I tried doing Q₁ = C_effV₁, but the answer was wrong.

 

[ooohffff]

Ok so since V1=V2+V3, I did Q1/C1 = Q2/C2 + Q3/C3. Solving for Q1, I get Q1 = C1[ Q2/C2 + Q3/C3].

Q2=Q3=q

Q1=C1*q[1/C2 + 1/C3]

Plugging in the numbers, when q = 15.9μC, I get Q1 = 1.4*10^-5 C. Does that look right?

 

[gneill]

Plugging in the numbers, when q = 15.9μC, I get Q1 = 1.4*10-5 C. Does that look right?

That looks right for the final charge on C1, yes.

 

[ooohffff]

That looks right for the final charge on C1, yes.

Thank you!