Griffiths E&M: Need Help with Plate Distance?

[ehrenfest]

Homework Statement

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?

Homework Equations

The Attempt at a Solution

 

[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.

 

[kdv]

Homework Statement

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?

Homework Equations

The Attempt at a Solution

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

 

[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}?