# Finding equivalent capacitance

1. Sep 21, 2010

### Acuben

1. The problem statement, all variables and given/known data

http://yfrog.com/mrcapdg

http://img819.imageshack.us/img819/1172/capd.th.gif [Broken]

Find equivalent capacitance

2. Relevant equations
whatever is in parenthesis is subscript
formula1: series: 1/C(eq)= 1/C(1) + 1/C(2) + 1/C(3) + ...
formula2: parallel: C(eq)=C(1)+C(2)+...

formula3: V=Q/C

3. The attempt at a solution

because of symmetry I decided that 3C has 0 charge (0q) and that top part has same voltage as the bottom part

charge split top and bottom equally

so I solved the problem "as if" 3C doesn't exist
so on the top series I get C/3 (using formula 1) and C/3 for bottom as well since it's in symmetry
and top and bottom form parallel so I get
2C/3 using formula 2

which is only half the answer

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Last edited by a moderator: May 4, 2017
2. Sep 21, 2010

### rl.bhat

For top branch 1/Ceff = 1/C + 1/2C = ?

3. Sep 22, 2010

### Acuben

o thanks for pointing that out, I made simple algebra mistake ^^