00:01
Okay, so we have a triangular pyramid that's made out of carbon.
00:05
We want to find its resistance.
00:07
We're given the resistivity is five times 10 to minus four oom meters.
00:12
Carbon does have a wide range of resistivities.
00:19
In general, and we're interested in the resistance for current flow in basically the vertical direction.
00:31
Okay.
00:31
So in general, the resistance is row times l over a.
00:40
So we need to calculate the area of that triangle.
00:49
So we have an equilateral triangle with side a.
00:56
You know the altitude of that triangle is root 3 over 2a.
01:09
So the area is one half of the base, which is a.
01:17
Times the height that comes out to be square root of three over four a squared.
01:30
All right.
01:31
So our resistance comes out like this...