00:01
So this is the problem dealing with a parallel plate capacitor, and we are asked to find various relationships concerning points in between the plates of the capacitor and also to try to find some numerical quantities.
00:17
Well, the basic idea that we're going to use here is that the electric field between the plates of a parallel plate capacitor is constant in magnitude and points from the positive to the negative.
00:29
So we can use this formula here to calculate the strength of the electric field.
00:39
It says that the change in potential is equal to electric field times a distance between the two sides of the airelope capacitor.
00:49
So we could use this to find out the electric field is equal to 56 volts.
01:00
That's delta v divided by point to four meters, and that ends up being 233 volts per meter.
01:18
Now, it's important remember that the electric field points from the positive to the negative.
01:25
So between points a and b, if an electron were to move between points a and b, it would be moving opposite the direction that it is experiencing a force, it would be moving with the electric field, but because electrons are negative, it's moving opposite the direction of the force.
01:43
So it's actually gaining potential energy.
01:47
So therefore, we must say that the electric potential energy at point a for an electron is less than the electric potential energy at point b.
01:57
Now, for a proton, they actually reverse the order of the points, and they say the electric potential energy or proton at point b, if a proton goes from point b to point a, it is also going against the electric force.
02:09
It is also gaining electric potential energy...