00:01
Here we're going to use conservation of energy to figure out how much energy kinetic -wise.
00:12
An electron must have in order to move from one point to another in a potential field.
00:20
So the potential is one -dimensional, and the curve is shown in blue on the figure.
00:26
And five different points are labeled with their voltages.
00:31
And the electron is starting at point a with some sort of kinetic energy, and it needs to get to point e.
00:39
Now, this problem reminds me a lot of problems you do in mechanics where somebody's on a bicycle, and they are going to try to go up a hill, just barely, just barely have enough energy to get over the hill.
00:56
That's kind of what's going on here.
00:58
There's a number of things that the electron is going to encounter, but the hill is actually point c.
01:11
The hill for the electron that it must overcome is at point c.
01:20
And how do i know that? electric potential energy goes as the charge times the potential.
01:30
And so if you're a negative charge, which an electron is, then a negative trough will look like a hill to an electron...