# Electric Field GRE Problem

## Homework Statement

http://grephysics.net/ans/9277/64

I'm confused. How can there be a charge density if the electric field is one dimensional?

## Answers and Replies

Think about charged sheets. What would be the electric field because of a charged sheet that is infinite in size?

so there is an electric field through e_x and e_y but it comes from the e_z field? like it says e_x and e_y are zero but say there was a point (1,0,0) (x,y,z). The "sheet" in the field would make there be an electric field in the x?

I don't know if i'm saying what i'm thinking clearly. I mean it looks the problem states that there is NO E field in the x and y domains, and yet if there is an E field in the Z domain, there can still be an E field in the X and Y because it is a distance r away from the Z. Dig?

What if the sheet of charge is in the x-y plane and is infinite?

nasu
Gold Member
I don't know if i'm saying what i'm thinking clearly. I mean it looks the problem states that there is NO E field in the x and y domains, and yet if there is an E field in the Z domain, there can still be an E field in the X and Y because it is a distance r away from the Z. Dig?

The "domain" is a region of space. There are no ex and ey domains.
Every point in the domain has coordinates x,y,z. The field is all along the z direction, in every point.
The field lines are all parallel to each other and to the z axis.
Te magnitude of the field changes linearly along the z axis.

Yous just need to see if this field can satisfy Maxwell's equations, and if it can, in what conditions.

Sorry about my previous reply. There was power shortage in my area. Ignore that reply completely. Try calculating the charge density in such a space. It weirdly turns out to be a constant. This means there is a uniform charge distribution throughout the space. I really don't think you can go in the reverse direction (assuming a uniform charge distribution in space and finding the field proportional to z). This seems very weird. The only positive thing here is that there does exist a charge density.