00:02
So we're looking at five equipotential lines here, and we have four points labeled on them, a, b, c, and d, and c are along the same echopotential line.
00:11
D is on another one, a little further down here, and b is in between a few.
00:15
And we want to talk about the lines, the electric field near those lines and near those points, and compare a few of them.
00:23
If we wanted to indicate the direction of electric field at any point, all you need to do is draw a line perpendicular from the equipent.
00:35
Potential line to the next echo potential line that is stepping down.
00:41
So it's going to go from the positive 5 to the 0.
00:43
It's going to go from, say, the positive 10 to the 5.
00:47
It's going to go from the negative 5 to the 10.
00:51
So at all the different points, it looks something like this.
01:00
Always perpendicular from the line they're on towards the next line that's stepping down.
01:05
And because this happens because the electric field is proportional to the difference in electric potential, and it's also inversely proportional to the distance that that change in electric potential occurs.
01:19
Another way writing this is saying that it's proportional to the negative gradient of electric potential.
01:28
So we can move on and answer the other questions with this information as well.
01:32
Is the magnitude of the electric field constant along each of the echocotential lines, meaning this echo potential line of plus five, is the electric field strength the same at, say, a as it is at c, that the same on the zero line all the way over here as it is at d.
01:51
Now, in my image, the scale is not perfect, but really, the closer these equipotential lines are, the stronger the electric field strength is.
02:01
Because it's about how much the potential changes and over what distance it changes...