Homework Help: Conceptual Parallel Plate Capacitor

1. Sep 28, 2008

ncm2

1. The problem statement, all variables and given/known data
Which statements are correct/incorrect for two oppositely charged, isolated parallel plates: (C=capacitance, U=stored energy, +Q and -Q = charge on the plates).
Correct Incorrect When the distance is doubled, U is unchanged.
Correct Incorrect Inserting a dielectric increases Q.
Correct Incorrect When the distance is doubled, C is halved
Correct Incorrect Increasing the distance, decreases the E field.
Correct Incorrect Inserting a dielectric increases C.
Correct Incorrect When the distance is halved, Q is halved.
Correct Incorrect Inserting a dielectric decreases U.

2. Relevant equations

3. The attempt at a solution
Now I don't know if I am misunderstanding the concept of Dielectrics or what, but this is what I believe:

A - I thought that this is false because PE = 1/2QV. And I know that the potential difference is dependant on r.
B - False because inserting a dielectric will not increase a charge.
C - True because C = (A/d)*constant
D - True because E = -Change in V/Change in X
E - True because the formula includes multiplying by a constant k.
F - False because Q = V*A*constant/d. Halving distance doubles Q
G - False. A dielectric is only an insualtor that can allow the capacitance to increase.