00:01
All right, so let's say we have a spherical shell with an inner radius a and an outer radius b, and it has a uniform volume charge density of 2 .11, nano -cools per cubic meter, and a is 1 .2, 3 centimeters, and b is equal to 3 .5 times a.
00:23
So we want to know what is the magnitude of the electric field inside the sphere.
00:27
And so e at r equals 0 is equal to 0.
00:31
Because there's no charge in that region.
00:33
And then at a over 2, once again, the electric field is going to be zero because there's still no charge enclosed in that region.
00:41
So we only start to get a charge at r or e at r equals a.
00:47
And even here, it's still zero because there's no charge enclosed right at that region.
00:53
All right.
00:54
So for part d at 1 .5a, so galsazelot tells us that e.
00:59
Dot a which is our surface which is 4 pi r squared should be the charge and close which we can write as row times four thirds pi r cubed minus a cubed divided by epsilon knot so we can see e is going to be row times r cubed minus a cubed over three epsilon not r squared all right so evaluate this at 1 .5 times a then what we have is 1 .5 cubed minus 1 times a cubed over 3 epsilon not times 1 .5.
01:40
Let me undo that...