00:01
Hi there, so for this problem we have an inverted emisphysical ball of radius art that carries an uniform surface charge sidma.
00:10
So we need to find the potential difference between the north pole and the center.
00:16
The situation is shown in this sketch right here.
00:24
So first we start by writing the potential at the center.
00:32
So that is going to be one over four times.
00:35
Xxpi xeux0 times the integral of sigma divided by the radius art integrated over the radius.
00:46
So in this case we will obtain from this, this is 1 over 4 times pi times epsilon sub 0.
00:54
And we can take out sigma and the radius art because those are a constant and we will have the integral of the differential in area.
01:04
Now in that case, we will have one over 4 times pi times epsilon sub 0 times sigma divided by the radius art of this of this semispheme.
01:20
And this is the integral of the differential in area, which is the area that we know is 2 times pi times the radius square.
01:27
So from this, if we simplify this expression, we will obtain sigma, the surface charge.
01:32
The charge surface area times the radius r and this divided by two times epsilon sub zero.
01:42
So now we note that the potential at the pole is equal to 1 over 4 times pi times epsilon sub 0 times the integral of the charge density divided by the radius integrated over the area.
02:00
Now from this we know that the differential in area is equal to 2 times.
02:04
Times pi times the radius capital r2d squared times the sign of theta times the differential in teta...