 In this video, we're going to be going over the very basics of Ohm's law. This is only going to be dealing with one supply and one load, so it's not going to get too complex. We're not going to get it into series or combination. Those are other videos for another time, but let's just look at Ohm's law. So what we have here is we've got a very basic circuit. We have a load, which is our resistor drawn here, and we have a source. Right now it's drawn as an AC source, but honestly it could be a DC source as well. It doesn't matter. It's the same principle. What we're going to do is we're going to assign some values, but before we do that, we're going to look at exactly what Ohm's law is. So Ohm's law is basically this relationship that talks about how current is directly proportional to the voltage of a circuit, and inversely proportional to the resistance of the circuit, meaning that the current flowing through this circuit will increase if this voltage increases. If the pressure increases, it will push more electrons through the pipe. And if the resistance increases, because it's sitting below a fraction here, we see that it's going to be inversely proportional to the current. So if this goes up, the current goes down, because it's going to have more resistance that it has to come across. Now you'll see Ohm's law expressed in two other ways as well. And what that is is it's a transposition of just this formula here. So we have V is equal to I times R. So all we've done here is cross multiplied. And so we can calculate what the voltage is in a circuit by having the current and the resistance. Now one thing to mention, though, is that while current is controlled by voltage and resistance, voltage is not necessarily controlled by current and resistance. It might be across the resistor if you're looking for a voltage across that. But on its own over here, this voltage is not being controlled by the resistance. This voltage here will not be controlled by the current. It does the talking, not the current and not the resistance. We can also transpose to figure out what our resistance is. We can take our current voltage, sorry, and divide it by our current to get our resistance. All three of these formulas are the same thing. They're just differently transposed. So we use them for figuring out different variables. Let's take a look at what I'm talking about. So if I start out with a circuit that's 120 volts, and I know that I have 30 Ohms of resistance, and I'm trying to calculate out I. So these three formulas, obviously I'm going to be using this one here. I is equal to V over R. So what we can do is we can take the 120 volts and divide it by the 30. I equals 120 divided by 30, and we get our current over here. That works out to be four amps. So that's how we would use the original formula, I is equal to V over R. Now if we're trying to figure out what our voltage is, and we're given the current and the resistance, we look here. And we say, OK, V is equal to I times R. That's the formula we're going to use. So we're going to take our current, 12 amps, and our resistance, the 20 Ohms, and determine what our voltage was. V is equal to 12 times 20, 12 amps, 20 Ohms, gives us this voltage here. Therefore, our V is 240 volts. So V is equal to I times R. That's a very common one that you see all the time. Now what if we have 120 volts and we have the current of 12 amps, but we want to determine what the resistances of these three formulas, R is equal to V over I, is the one we're going to be looking at. So we've got our voltage 120 volts divided by our current. So 120 volts divided by 12 amps will give us what our resistance is. And in this case, that works out to be 10 Ohms. So that's a walkthrough of just the three different ways you can transpose Ohm's law and how you would use that. It can get a little more complex once we start throwing other resistors in the circuit, whether they be in series or parallel. But this is one of the foundational formulas that you will need to determine anything else in the electrical field. We always start with Ohm's law.