 In this video, we're going to talk about the difference between EMF, Electromotive Force, and potential difference. It can be quite confusing because they're both measured in volts, but they both have different purposes. So let's go through and talk about them. So right now, we have ourselves a basic circuit. We have a battery here, negative terminal, positive terminal. We have a resistor over here. We have a circuit that's completing it all through here. So we have a source of voltage, and then we have something that is using the voltage. That's kind of the difference between EMF and potential differences. As it's most simplest, we would say that EMF is a source of voltage, and then potential difference is the voltage that arises from a use of voltage. But let's get a little deeper into it. So EMF can be defined as when something takes a different form of energy and converts it into electrical energy. All right, so what we're doing is we're taking some other type of energy, whether it be chemical, mechanical, magnetic, and we're taking that energy and we're converting it into an electrical form. Great example of this is the battery. We're taking chemical energy and we're converting it into electrical energy. Another example, a wind turbine. We're taking that mechanical energy of it spinning around and around and around, and we're converting it into electrical energy. Another great example of this, a hydroelectric dam. It's taking all this potential energy that sits up in the reservoir as it travels down through the penstock, spins the turbine, and creates electrical energy. So again, anytime we take some other form of energy and convert it into electrical energy, that creates an electromotive force. Now potential difference, on the other hand, is over here. This is the energy that's getting used, and what we can say with potential difference is that it is converting electrical energy and converting it into a different form of energy. So remember with EMF, we took another form of energy, converted it to electrical, then it did its thing, and it does its thing across this resistor here, then it takes that electrical energy and converts it into another form of energy. Some great examples of that. Heaters, so it's taking the electrical energy as creating heat as it flows through the resistor. An electric motor, so it's taking that electrical energy and creating mechanical energy as it starts to turn the rotor of the motor. And the almighty light bulb. So it's taking this electrical energy and converting it into light energy. So that would be an example of potential difference. Now again, the thing that gets confusing with potential difference is they're both measured in volts. So however, EMF is the voltage used to create some sort of energy, and potential difference is the volts that is being used by the source. So there you go, that's the difference between an EMF and electromotive force and PD or potential difference. Again, both measured in volts.