What is the potential difference between points a and b?

[max1205]

Homework Statement

Six identical capacitors with capacitance C are connected as shown in figure 30.68 (attachment). What is the potential difference between points a and b?

Homework Equations

C=Q/V

The Attempt at a Solution

The Cequivalent = 3/2 C

Therefore, Q = CV
= (3/2C)(12)
= 18 C

since capacitors in parallel have the same potential difference, the two capacitors that are in parallel between point a and b have the potential difference,

V = Q/C
= 18C/(C)
= 18

Thus, the two capacitors between point a and b, have a combined potential difference of 36V.

Is this correct?

 

[max1205]

any ideas?

 

[jackie48]

i don't know, i agree with most of what your saying, but haven't done any calculations yet.
when i read 'potential difference' the first thing that i think of is subtraction.
since both capacitors have the same potential, then the difference of their potentials is zero.
but i could be wrong... and probably am.
i only have one attempt remaining in mastering physics so i don't want to test this theory until someone else does.

 

[jackie48]

i was right,
answer is 0 V

 

[max1205]

got it, thanks!