 In this video, we're just going to quickly walk through how to get your volt drops across each resistor. We've got a branch that's got three resistors in series and another branch that has three resistors in parallel, and then we're going to discuss quickly how to determine what the volt drop is from different points. So if I took a volt meter from A to D or from B to C, how to determine the volt drop and the polarity in regards to that. Now in order to do that, let's assign some values here. So let's just turn my pen on and go with, let's pick a nice easy voltage, 120 volts for my source. Then down for this branch, let's give us 10 ohms, 20 ohms, 30 ohms. And then for the branch below it, let's just give a big one that say that this is 1k ohm. Let's say that this is 2.6k ohms. And let's say that this is like 4.2k ohms. And the reason why I picked such outrageous voltages is just to show that you're not going to get such an outrageous change on voltage across each branch because you're dealing with 120 volts from this point to this point. So you're going to get a proportional drop across each resistor. And same thing over here, you got 120 volts from this point to this point, you're going to get a proportional volt drop across each one of those. So first up, let's look at our first branch here. We need to determine what the current is going through this branch to determine the volt drops across each one. There's other ways to do it, but for all intents and purposes right now we'll use that method because that seems to be a fairly easy one. So I have 30 plus 20 plus 10, so I have 60 ohms in total, which means if I took 120 volts here and divided it by 60 ohms across here, I'm going to get my current, which is going to be 2 amps. So let's just change my color. Let's go with a nice green. So I've got 2 amps flowing through this branch. Then I can determine my volt drop just by going 2 times 10 gives me 20 volts. On that branch, I'm going to go 40 volts on that branch, 2 times 20. And I'm going to go 60 volts on that branch. So I've got my volt drops across each one of them. Now before I leave this area, let's get one other thing figured out. It's my polarity because that's going to come in very important when we start to determine volt drops. So current flows from negative to positive. Current flows through a load from negative to positive. So therefore, going through this, that's negative positive, negative positive, negative positive. So I've got my polarities. So now we've got this branch here is completely done. Let's move on to the second branch. So in this branch here, I'm dealing with 1K ohm plus 2.6K ohms plus 4.2K ohms. So if I add all those up together, I end up with 7,800 ohms or 7.8K ohms. And from there, I can determine what my current is by going 120 volts divided by 7.8K ohms down here. And that will give me a current of 15.4, let's just write that down, 15.4 milliamps. So I have 15.4 milliamps traveling through these resistors, which now I can determine my volt drops across each one by using Ohm's law. This current times this will give me my voltage. This current times this will give me my voltage. And this current times this will give me my voltage. So doing the math, this volt drop here ends up being 15, let's turn our pen on, ends up being 15.4 volts. This volt drop across here ends up being roughly around 40 volts. And this voltage across here ends up being 64.6 volts. So now again, we're going to just put our polarities in. Our polarities are going to be the exact same that they are in this branch here. I've got a negative, positive, negative, positive, negative, positive. So there we go. We've got our volt drops across each branch. Now we're going to determine what the voltage is from point to point. So if I pick, say, point A to point D, or if I pick point B to point C, it all works out the same way. So we're just going to take what I do is take what I call a current drive around. So let's say I'm trying to figure out from point A to point D. The way I look at it is this. I start at point A and I'm going to drive from point A all the way down and end up at point D. That's going to determine what my volt drop is. So if I do this, you notice that I'm starting with a negative here. So I'm starting here. I'm going to drop off 20. So negative 20. And then I'm going to come along here and you notice I'm going to see the positive sign here. So I'm picking up 15.4 and I'm picking up 40 volts. And that will give me my end voltage, which is a positive 34 or sorry, 35.4 volts. Now it should work the other way too. If going from this point to this point got me 35.4 positive, then I should be able to get the same thing going this way all the way to this way. So let's add that up. So if I go this way, I'm picking up 40. I'm picking up 60. And then I'm dropping off 64.6. So by the time I get there, I end up with the same voltage. I end up with a voltage of 35.4 volts. So that determines what my volt drop will be at any point. So I can do the same thing. Let's just do one more quickly. If I go from B to C, I'm going to go from B. I'm going dropping off 40, dropping off 20, picking up 15.4. And I end up with a voltage of negative 44.6 volts because I ended up dropping off more than I picked up. Again, if we go the other route, we should be able to get the exact same answer. If I go this way from B to C, I pick up 60. I drop off 64.6 and I drop off 40 and I end up with roughly around negative 44.6. So that's how you determine volt drops across an unbalanced bridge circuit from different points. It's just a matter of getting your voltages, getting your polarities, which is so very important. And then from there, you can just take the drive from one point to another.