00:01
All right, so for this one, you have two concentric spheres.
00:09
This one has a radius r1, and then this one has a radius r2, and then the inner one, i'll call it r1, q1, is 4 .00 times 10 to the minus 8 kuloms, and then the charge on the outer is 2 .00 times 10 to the minus 8 coulomes.
00:38
And then the goal is to get the electric field at an r within here and then an r outside of it.
00:47
So for a case a, r is equal to, what was it again? what was it again? 12 centimeters and 20 centimeters.
01:08
So i'll just go ahead and write it in meters, 12 .12 meters, and then i'll write up b .r equals 0 .2 meters.
01:18
So through a gauce's law argument for, oh, why, what happened? okay.
01:25
So for a gauze's law argument for this inner one, you basically can draw your galsian surface, ask what's inside, and then use that to evaluate gauce's law.
01:35
And the problem would basically go the same as if this were the intercharge was all concentrated at the center.
01:44
And so it would proceed in the same way that you would derive the field for that, which is a familiar result.
01:57
E is 1 over 4 pi epsilon not times q1 over r...