Capacitor Circuit: Equivalent Capacitance & Charge

[elleeyeesay03]

Homework Statement

For the capacitor circuit shown below:
A. Find the equivalent capacitance
B. What is the charge on the 3\muF capacitor?

Homework Equations

Q= C\DeltaV

Parallel= C1 +C2+C3
Series= (1/C)=(1/C1)+(1/C2)+(1/C3)

C1= 8\muF
C2= 5\muF
C3= 3\muF

The Attempt at a Solution

 

[gneill]

Hi elleeyeesay03, welcome to Physics Forums.

Have you made any attempt to simplify the circuit? Can you identify any serial or parallel combinations of capacitors?

 

[engineertech0]

C2 & C3 are in parallel so they would be equal to 8uf by adding 3uf + 5uf. You will then consider that once capacitor and take it in parallel with C1. Having to 8uf capacitors in parallel would yield you an equivalent of 4uf as the current would be splitting between the two.

 

[gneill]

C2 & C3 are in parallel so they would be equal to 8uf by adding 3uf + 5uf. You will then consider that once capacitor and take it in parallel with C1. Having to 8uf capacitors in parallel would yield you an equivalent of 4uf as the current would be splitting between the two.

While C2 and C3 are in parallel, yielding an 8μF equivalent, the resulting equivalent capacitance is in SERIES with C1, not in parallel with it. The net equivalent capacitance is indeed 4μF though, as you stated.