00:01
So in this problem we have three point charges, and they all have the same charge, 1 .2 microcoules.
00:09
And they're brought in from infinity to form an equilateral triangle, each with the side of 0 .4 meters.
00:17
So what we want to do is we want to find the total potential electrical energy of the system.
00:22
So the way that we're going to do that is we're going to use this formula here that we have to find the total electric potential energy, which would be the sum of the individual potential energies of each pair of the point charges that are in the system.
00:40
So if we go ahead and write out this formula, what we have is q0 over kulam's constant, which is 1 over 4 pi times epsilon knot.
00:54
And this will be multiplied by a summation.
00:58
So we have qi divided by ri, where we're taking each charge and dividing it by the distance from the original charge that will define perhaps the origin.
01:17
So now what we want to do is because we know in this problem, we're looking at three different pairs.
01:24
We have u1, 2, u1 3, and u2, say if we call this 1, q2, and u2, say if we call this 1, q2, and q3.
01:38
We know that all these potential energies within these pairs are going to be equal since we're dealing with the same charge and the same distance as it's in an equilateral triangle formation.
01:49
So this means that we can simplify our summation a little bit...