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eprparadox
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Homework Statement
Two parallel-plate capacitors with the same plate separation but different capacitance are connected in parallel to a battery. Both capacitors are filled with air. The quantity that is NOT the same for both capacitors when they are fully charged is:
A. potential difference
B. energy density
C. electric field between the plates
D. charge on the positive plate
E. dielectric constant
Homework Equations
## C = \frac{Q}{V} ##
## C = \frac{\epsilon_0 A}{d} ##
## U = \frac{1}{2}CV^2 = \frac{Q^2}{2C} ##
The Attempt at a Solution
The answer is listed as D.
Because the capacitors are hooked up in parallel and stay connected to the battery, I know the potential difference (A) will remain the same (The electric field will also then remain the same (C)).
Dielectric constant is the same (E).
So it's between B and D.
We're told the capacitances are different and know that ## U = \frac{1}{2}CV^2 ##.
If the capacitances are different, then it seems that the energy densities should also be different. But I also think the charge on each capacitor should be different. So I think both B and D won't the same!
Any thoughts on where I'm going wrong?