Electrostatics Question

[Cujo]

I just started my electromagnetism class last week, and I'm having trouble of identifying this question to be either a Electric Field Charge Distribution or a Gauss's Law question?

"Calculate the electric field at the surface of an infinite plane having a surface charge density of 103 C/m^2"

[CatalinaWOW]

Whichever way you think of it you must recognize the simplification that "infinite plane" makes.  The field is nice an uniform, perpendicular to the plane and identical in every square meter.  So you can just solve the problem in one square and with the knowledge that no effects from that square extend out of the rectangular tube extending perpendicular to that square.

[ejeffrey]

That is a classic Gauss's law question with one clarification: you can't find the field at the surface itself which is undefined in this instance.  You can only find the electric field on either side of the charged surface.

The first thing to do is to use symmetry to realize that there can be no transverse component of the field, the only field is normal to the charged surface.

Then construct a Gauss's law surface such as a cylinder such that every surface is either parallel to the electric field or perpendicular.  The total flux through the perpendicular faces has to equal the charge inside. Don't forget to count the flux through the faces on both sides of the charged plane.