 In this video, we're going to talk about polarity basics. Polarity is such an important topic when we're discussing electrical, so it's very important that you have your head wrapped around it. So a great place to start is we're going to start with these different cups. We have cup A, B, C, D, and E. And each one of these cups is going to have a different temperature. But what we're going to first do is we're going to present a reference cup. So in this case, we're going to use cup C as our reference point, and it's going to be around room temperature. So we've given cup C 20 degrees Celsius, that's the room temperature. Cup B and A are going to be above room temperature and cup D and E are going to be below room temperature. So here we go. We've got cup C 20 degrees. That's our reference point. Cup B is 30 degrees Celsius. Cup A is 40 degrees Celsius. Cup D 10 degrees Celsius. Cup E 1 degree Celsius, which to me would seem like the more refreshing of the five cups to drink, but just work with me here. So what we're going to do now is I want to look at each one of these cups with respect to cup C. Now, if we look at cup B, we can agree that it is 10 degrees more than cup C. Same thing with cup A, it is 40 degrees, sorry, 20 degrees more than cup C. So if we're talking about this in terms of polarity, we would say that cup B is positive with respect to cup C because it is greater than and cup A is more positive than cup C and with respect to the fact that it is 20 degrees more. Now, if we look at cup D and E, they're below 20 degrees when a 10, one at one. So we would say with respect to cup C, cup D would be negative with respect to cup C and cup E would be negative with respect to cup C because they are less than 20 degrees Celsius. So that's all well and good when we're talking about different temperature cups. But what does that have to do with electrical? Well, let's throw some resistors at us. So I've got resistor A, resistor B, resistor C, resistor D and resistor E. And again, what we'll do is we'll start with a neutral resistor. So we'll start with this guy right here, resistor C. And then we're going to start adding some charges to resistor B and A and resistors D and E. Neutral charge means that it has no neutral. It does not have any positive or negative charge at all. It is just flat line neutral. So what we'll do here is we're going to add some charges to it. So we're going to say that this has and this is just work with me on this one, but this has 50 less electrons. It has a deficiency of electrons, which means it has a positive charge. This one has 100 less electrons or has a positive charge of 100. This one has an excess of 50 electrons or a negative charge. And this one has an excess of 100 electrons or a negative charge of 100. So again, this is just like the cups. But what we're going to be doing now is we're going to be looking at these with respect to the neutral element. And then we're going to talk about them with respect to each other. So in this case here, we see that plus 50 and 100, you could treat neutral like zero are positive. So with respect to resistor C, B and A are both positive. Here we see that we have negative 50 and negative 100, which means they're negative, obviously, which means that with respect to resistor C, this is negative and this is negative. Now, you notice I keep using this term with respect to because what we can do is we don't always necessarily have to have a neutral point be a reference zero degrees or no neutral charge or anything. You will, as you proceed through your electrical career and electrical schooling, see that you've got different charges at different points. So we can see that point A and point B. And I could ask what point A is with respect to point B. All right. So if I look at that, this is plus 100. This is plus 50. This has got more than this does. So therefore, resistor A is positive 50 with respect to resistor B because we have 100 here and 50 here. The difference between 150 is 50 and A is positive with respect to B. Now, just the opposite, I could ask what resistor B was with respect to resistor A. So in that case, I could say that B is negative with respect to resistor A because it is less than 100. So it's more negative than the 100. So resistor B is negative with respect to resistor A. And again, I could do the same thing the whole way down. I could say that resistor D is positive to resistor E because it is less negative. So it's negative 50 as opposed to negative 100. Or I could say that resistor E is negative with respect to resistor D because it is more negative than this one. I could also say, I mean, I could go through the whole gambit of it and just keep going that resistor B is positive with respect to resistor D by 100 because we have the 50 and then the other 50 going the other way. So there's 100, I want to say degrees, but there's 100 electron difference between the two of them because you know you have 50 to neutral and you have another 50 that way. So the difference between the two is 100. So I could say that B is positive by 100 with respect to D or D is negative with respect of 100 to B. So it's all to do with your reference point. Which point is your reference? Is it what you're going to determine if it's a positive charge or a negative charge?