- #1
- 256
- 18
Homework Statement
Capacitor 3 in Figure (a) is a variable capacitor (its capacitance C3 can be varied). Figure (b) gives the electric potential V1 across capacitor 1 versus C3. The horizontal scale is set by C3s = 20 μF. Electric potential V1 approaches an asymptote of 10 V as C3 approaches infinity. What are (a) the electric potential V across the battery, (b)C1, and (c)C2?
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