Finding the potential across capacitors in capacitor-only circuits

[Gourab_chill]

Homework Statement

I have been asked to find the potential difference between points M and N in the given figure. The circuit is in the attachment.

Relevant Equations

Q=CV

I tried to attempt it by applying KVL to both the loops.

I tried to find a possible charge distribution for the capacitors. I guess this is right.

On solving I get:

from what I know potential difference between M and N is Q1/C2
but the solution is given as:

Where am I wrong?

 

[TSny]

Welcome to PF!

You have a sign error in one of your first two equations.

 

[Gourab_chill]

Welcome to PF!

You have a sign error in one of your first two equations.

thanks