00:01
Okay, we're investigating gauss's law here.
00:05
We're using gauss ' law to think about where the excess charge and a conductor goes.
00:10
So let's draw our conductor here.
00:16
And we're told that it gets negatively charged, right? let's see.
00:29
Yeah, negative charge.
00:30
Okay.
00:31
So where does the charge go if it's free to move around? and something they tell us here is that the electric field in a conductor is zero everywhere inside the conductor.
00:47
So that's an important thing to know.
00:51
So question one, we want to think about what is the amount of excess charge enclosed by the dashed surface just below the surface of the conductor.
01:08
So how much charge is contained by this black dashed line we've drawn? and we want to use the fact that electric field equals zero.
01:17
Let's use gauss's law, right? the closed surface integral of e .da equals q enclosed and closed over epsilon nut.
01:40
So if we know that the electric field equals zero, that makes this entire left -hand side equals zero, right? q enclosed or epsilon not.
01:54
We know for a fact that epsilon not is not equal to zero.
01:58
That's just a constant.
01:59
So for this equation to be true, the enclosed charge has to equal zero...