Hey, guys. So in this video, we're going to cover two really important concepts: the resistance of a conductor and this really powerful equation that you need to know called Ohm's law in order to solve problems. Let's go ahead and check it out. Before, when we talked about charges that flow through a conductor, we sort of pretended that these electrons or charges could pass through this conductor sort of unobstructed. They were freely able to go from one side to the other. The reality is that they're not that simple because inside of a conductor, there are atoms. And as these electrons are traveling through this conductor, they're bouncing off of the atoms inside of that conductor, and all of those collisions that take place sort of create this internal friction that resists the amount of charges that can go from one side to the other. In other words, this internal friction resists the current. So if you have a conductor and you place some voltage or some potential difference across it, and you have these atoms that are trying to cross from one side to the other, the relationship between the current and the voltage is given by this equation where I is equal to V, but you have to divide it by this term called R. Now this R term is called the resistance. And this resistance here is basically the ability for a conductor to resist the amount of charges that are trying to make it across in a certain amount of time. The units for this resistance are in ohms, and it's given by this Greek letter, capital Omega. And what this resistance represents is that the larger the resistance of a conductor, the smaller amount of current can pass through it. The smaller amount of charges can pass through in a specific amount of time. So we have this relationship between I, V, and R, but more commonly you'll see it written in this way. And this is called Ohm's law. This is really important. You definitely need to commit this to memory. This is V equals I times R. This is kind of like the F equals MA of physics 2. So definitely commit V equals IR to memory because you're going to be using it a lot in the future. Alright, guys. That's basically it. That's the equation that you need to know. Let's go ahead and work out some practice problems right here. Okay? So we've got a conductor, and we have a voltage of 10 volts across it. We're told that 6 microcoulombs of charge flows through it every 1.5 seconds. We're supposed to figure out what the resistance of this conductor is. So as a variable, we're not in other words, we're trying to figure out what R is. And we have only got one equation to use so far. So we're going to use Ohm's law. V equals I times R. If we rearrange for this, we know that the voltage divided by the current is equal to the resistance. So we have what the voltage is. That's just the 10 volts. So how do we figure out what the current is? Because we're not told what that explicitly is. So what we have to do is we have to say that the current is going to be the charge divided by the amount of time. So remember we can use this I = ΔQ Δt from a previous video. So if we have an amount of charge that's flowing through, 6 times 10 to the minus 6, divided by an amount of time, which is 1.5 seconds, then this is just going to be 4 times 10 to the minus 6, and that's going to be amps. Remember that current is going to be amps. Okay? So now we have to plug this basically back into this equation, and we have that the resistance is equal to 10 volts divided by the amps, which is 4 times 10 to the minus 6. And we have a resistance that's going to be 2.5 times 10 to the 6, and that's going to be in ohms. That's sort of like the symbol for that. Alright? So that's how you figure out the resistance of a conductor. Alright, guys. Thanks for watching. Let me know if you guys have any questions.
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Resistors and Ohm's Law
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