# Calculating D field in a region between two charged surfaces

1. Nov 2, 2015

### MNightShamylan

1. Question: There is a wire with charge, surrounded by a metal cylinder with opposite charge. There is a dielectric surrounding the wire, going out half way to the outer cylinder. Calculate the D field in the region between the cylinder and wire.

2. Relevant equations:

Gauss's law for displacement: integral D * da = Q(free enclosed)

3. The attempt at a solution:

It seems to me that there will be a piecewise solution, one for the gaussian surface inside the dielectric and one just outside it (but just inside the outer cylinder). If the surface area of the gaussian cylinder is 2pirL, then is the D field just Q/(2pirL)? It seems like this is just way too simple, and I feel like I'm missing something. I also don't see how this takes into account the gaussian surface inside the dielectric, which should be different. Any guidance would be appreciated/

Last edited by a moderator: Nov 2, 2015
2. Nov 8, 2015

### Greg Bernhardt

Thanks for the post! This is an automated courtesy bump. Sorry you aren't generating responses at the moment. Do you have any further information, come to any new conclusions or is it possible to reword the post?