Alright, guys. So in this video, we're going to be talking about the electric potential. We talked about the electric potential energy between two charges. And even though those two things sound similar, we're going to see how in this video they are different. Let's check it out. Electric potential is sometimes just simply called potential, and electric potential energy is sometimes just simply called potential energy. It's kind of assumed that we're talking about electricity. So a lot of people just don't even say electric potential energy. We just say potential and potential energy. But one important distinction to make is that even though these two things are related and they sound the same, they actually represent different things. So we have to be very careful about our word choices and how we use these terms. Now, the best way to understand the difference between potential and potential energy is to go back and talk about electric fields. So, we said that basically a single charge, whether it was a positive or negative charge, let's assume it's a positive charge right here, emitted these field lines, these electric field lines, and basically, these field lines were just information, and this information or field told charges that were in the vicinity how much force to feel.

What happens is that a single charge alongside producing an electric field also produces something called an electric potential, and it's very similar to how it works. So, if you have a positive charge at the same time it's producing this electric field outwards, telling other charges how much force to feel, a positive charge is also emitting some information, a field called a potential, which, by the way, has the symbol V. And this symbol basically tells charges how much energy to have or how much energy to feel. And the thing is, we were talking about single charges in which this was like a big Q. We said that that was the producing charge and then it emitted these field lines and basically nothing happened unless you actually dropped a second charge inside of here, a small q. And once you had a second charge, all of a sudden, there is a force on this thing because if you have some electric field lines that point in this direction, and if you drop a charge here, then, for instance, if it's a positive charge, then this is going to feel a repulsive force like this. And we have the relationship between the force and the electric field that was just given as F=qE.

Similarly, for potential, this single charge sets up a field called an electric potential, and once you drop a second charge inside of this potential, now there is energy. These two things are different, but the mechanisms in which they sort of set up these force fields and energy fields are very similar. We said that the force that we could calculate on a charge from an electric field is just given by this equation: F=qE. Well, it's very similar for energy. What happens is once there's a second charge that you put in between these two things. Now it basically creates some electric potential energy, which we know the equation for, and this electric potential energy is given as U=qV in which, in the case of Coulomb's law in the case of electric fields, this E represented the strength of the electric field that this feeling charge was put inside of. Well, this V is the strength of the energy field that is put inside of.

Another way you might see that is actually the potential, sometimes the potential field. So basically, we know that the q that this little q here always corresponded to the q that was feeling the field that it was put inside of. So, in other words, this q is always the feeling charge. Well, it's the same way with the potential in this formula right here: U=qV. This q always represents the thing that is feeling the potential at that specific spot.

Alright, so I just want to go ahead and wrap up everything really quickly, once more. So you have a single charge. It produces something called an electric field, and that field tells charges that are inside of it, how much force to experience. And once that second charge is put there, there's force called Coulomb's Law, and it's given by this equation or kqq2/r2 where r is the strength of the electric field? And that q is the feeling charge. Well with the potential, it basically does the same exact thing because it's for energy and the equation is slightly different.

A single charge produces an electric potential out here. And once you are in that potential it tells charges inside of it how much energy to have. And once there is a second charge, all of a sudden now there's energy. There's potential energy between these two charges that potential energy is given as U=qV or U=kQq/r where that V is the strength of the energy field or the potential field. And this little q is also the feeling charge. Okay, so the unit of this electric potential is called the Volt, and it's given by the letter V. And this V is actually defined as one Joule per one Coulomb.

Now we have to be very careful here because this V is the symbol for both the electric potential and the unit. So, for example, it would be perfectly sensible to have an equation like this: V = 3 volts. This would be perfectly sensible. It was just some guy who decided hundreds of years ago that the symbol for the letter and the unit was going to be the same. So this right here is the symbol for electric potential. Whereas this right here is the unit. So just so you know, don't get confused between those two. And that's basically all we need to know about the electric potential. Let's go ahead and check out an example. We have a five and a three Coulomb charge that are separated by some distance right here.

So if the five Coulomb charge feels 200 volts from the three Coulomb charge, what's the potential? Great. So we have these two charges right here. This is going to be a five. Coulomb charge, and now we're supposed to figure out what is the potential energy on the five Coulomb charge. So in other words, we're trying to figure out what U is. We know that U is just going to be K Q1 Q2 / r. Here's the problem though: we could use this, we could try to use this potential energy right here to figure out what the potential energy of this five Coulomb charge is. The problem is, we actually don't know what this r distance is, so we can't use this potential energy formula.

Instead, we're going to have to use a different potential energy formula, which is that U is equal to qV. So we have with the charges. This charge corresponds to the feeling charge, and we know that the five Coulomb charge is feeling 200 volts from this charge over here. So, in other words, this is actually the producing charge Q, and this is actually the feeling charge little q. So this is actually going to be the charge that we use in this formula. And what we're doing is we're basically saying this producing charge here is producing some potential field, some potential out in this field here. And this little q is feeling it.

Okay, So that means that this potential energy is just going to be the five Coulombs times the potential, which is 200 volts at the specific point. So at right here, the potential is 200 volts. So that means that the potential energy is going to be five times 200 which is equal to 1000, and that's it. So basically, just let me know if you guys have any questions, let's go ahead and do some examples.