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## Homework Statement

Capacitor 3 in Figure (

*a*) is a variable capacitor (its capacitance

*C*3 can be varied). Figure (

*b*) gives the electric potential

*V*1 across capacitor 1 versus

*C*3. The horizontal scale is set by

*C*3s = 20 μF. Electric potential

*V*1 approaches an asymptote of 10 V as

*C*3 approaches infinity. What are

**(a)**the electric potential

*V*across the battery,

**(b)**

*C*1, and

**(c)**

*C*2?

http://edugen.wileyplus.com/edugen/courses/crs7165/art/qb/qu/c25/fig25_44_wiley.gif

## Homework Equations

C=q/V=(permitivity constant)A/d

## The Attempt at a Solution

I've been stuck on this problem for 1 hour. I just can't figure it out. I can't figure out the voltage of the battery, which is supposed to be 10V.

What I've tried to do is look at when C3=infinity which means that the distance between the capacitor is 0, so its just a wire. Then I get a parallel circuit with C1, and C2, where the voltage going through C1 is 10V. This makes a series circuit with C1, C2. So I know that the voltage of the battery = 10V + the voltage through C2. I can't figure out how to get 10V for the battery