00:01
Alright, so let's say we have a conducting rod with two points a and b on either side of it, and it's moving with the speed v in a field that has a length l, and the magnetic field points into the page everywhere.
00:15
So we want to know what point a or b has an excess of positive charge.
00:23
So the lorentz force requires that point a will have more electrons, or more negative charge, because the negative charges are going to move to the left, positive charges move to the right.
00:36
And we want to know what field, what direction does the electric field point, so it'll basically be from b to a.
00:45
And then for part c, we want to know when the charges in the rod are in equilibrium, which is the magnitude of the electric field within the rod.
00:50
So basically what we want is q times v cross b, which is the lorentz force, to equal q times e, because then they're in equilibrium.
00:58
So we can cancel these, and we can see the magnitude of e is just going to be v times b...