Griffiths 4.19

1. Mar 18, 2008

ehrenfest

1. The problem statement, all variables and given/known data
This question refers to Griffiths E and M book.

I am confused about what the answer should be in terms of. Usually he gives us all constants that might be needed in the answer. But we need to know that distance between the plates here don't we?

2. Relevant equations

3. The attempt at a solution

2. Mar 18, 2008

CompuChip

I haven't looked at the problem, but maybe the answer doesn't depend on it. You can just introduce a variable for it (like, call the distance d) and see if it cancels out in the final answer.

3. Mar 18, 2008

kdv

he asks by what fraction the capacitance is increased so the distance will cancel out.

4. Mar 18, 2008

ehrenfest

He also asks about E, D, and P. I am pretty sure we will see a d in the answer (where d is the distance between the capacitors).

Another question. Do we know that the dielectric does not affect the electric field in the vacuum regions between the plates i.e. is the E-field in those regions E_{vac}?

Last edited: Mar 18, 2008