00:01
Okay, so we've got this situation here, and we want to use gauss's law to find the electric field.
00:07
So we're saying what's the symmetry property of the charge distribution here? the symmetry property is that we're going to have radial symmetry in the electric field, and it's going to be symmetric about the central axis of the inner cylinder like this.
00:29
Part b asks what is the direction of the electric field? that follows the electric field moves in the direction that a positive charge would move in.
00:37
The positive charges in here are going to be attracted to the negative charges here, and so the field is going to move radially outwards.
00:51
For part c, how many different regions of space is the charge distribution determined? so we can see we're going to have to have an electric field inside the inner cylinder, so that's one region, and then between the inner cylinder and the outer shell, that's another region, and then outside of the outer shell.
01:07
So there are three different regions.
01:12
Although in the third region, it's going to be zero because the enclosed charge is zero, so it's easier to determine that.
01:21
So there's two that we need to really figure out.
01:23
Part d says for the region r being less than a, so that's inside the inner cylinder, calculate the flux through your choice of gaussian surface...