1. The problem statement, all variables and given/known data The plates of an air filled parallel plate capacitor with a plate area of .0016 m^2 and a separation of .009 m are charged to a 145 V potential difference. After the plates are disconnected from the source, a porcelain dialectric with k = 6.5 is inserted between the plates of the capacitor a) what is the charge on the capacitor before and after the dialectic is inserted? b) what is the capacitance of the capacitor after the dialectic has been inserted? c) what is the potential difference between the plates of the capacitor after the dialectric is inserted? d) what is the magnitude of the change in the energy stored in the capacitor after the dialectric is inserted? 2. Relevant equations q = vc Ue = (1/2) CV^2 c = epsilon 0 * A / d 3. The attempt at a solution so for A) I have q = vc ---> q = (145) ((epsilon 0 * A )/ d ) plugging in, q = (145) (8.55x10^-12) (.0016) / .009 = 2.204 x 10^-10 my books answer was 2.28 x 10^-10 They didn't even answer the second part of question A, which was what is that charge after. Since they only listed "2.28 x 10^-10 " as the answer to A, I'm going to guess that is the before AND after charge? Is this because if you disconnect from source, inserting the dialectric isnt going to change anything? Why was my answer off from the books, did I even do it right? I mean it was just plugging in the equation but still, it seems wrong to me.. Anyways I thought my formula would now be q = kvc with k being 6.5 but I guess not?