Thevenin Equiv with just Capacitors

[kostoglotov]

Homework Statement

imgur link: http://i.imgur.com/TWB5rRu.png

Homework Equations

The Attempt at a Solution

I can find the equivalent capacitance, 10F, but I'm not really sure how to find the equiv. Thev. voltage. I figured that with the voltage source present, half the voltage will be lost across that first capacitor (since the next two parallel caps have an equivalence of 5F as well), so therefore at the very least in the Thev equiv circuit we should be seeing 22.5 V across the terminals. But the answer in the back gives Vth as 15V, less than 22.5.

How does one find the Vth?

 

[gneill]

Hmm. I wonder if at some point the problem was changed slightly without the answer key being updated. If the voltage source was 30 V rather than 45 V, then the given answer would make sense. I can't see the open circuit voltage being anything other than 22.5 V.