All right and welcome here to the second part of inductance, inductive reactance. And in this slide here or in this portion of the course we're going to be talking about inductive reactance. And inductive reactance is the opposition of a electron flow in a an alternating current circuit. Notice I said alternating current, all right. And XML. We have a formula for XML and XML represent inductive reactance and our formula is two pi FL.

Now if you've taken previous courses, we know that pi equals 3.14. So two pi would be 6.28. Okay, ask here would be the frequency of the AC white waveform, and l would be the value of the inductor. All right. All right. So XML is inductive reactance or I should say XML represents inductive reactance.

The formula for X sub l is right here to pi FL. All right. All right, let me clear off the slide we'll go on to the other bullet points. We're also going to look at how XML reduces the amount of alternating current and an alternate Current or AC circuit, we're going to look at series or parallel inductive reactance is we're going to apply ohms law texts about. I'll show you how to do that. And applications of inductive reactance.

And wave shaping of Isa Bell Isa Bell is the voltage across my coil or my inductor, all right, and that's induced by a sine wave currents alright or any alternating current fluctuating current. As we stated in the previous section, all right coils. If I put a direct current or a direct voltage across a coil, the current is limited by the resistance of the windings I and we got to be careful on that and then we'll we'll talk about that a little Bit more when we talk about transformers and so forth. But that said, that's what we're going to cover here in this, this portion of this inductance and inductive reactance course. Alright, see you in the next slide. All right, right here we have three circuits.

And we on these two here, we have an alternating voltage, which again, provides an alternating current over here, that's a battery and we have a direct current. So we know from actually at the review that we had at the very beginning of this course, we have current that flows back and forth, like that. That's my alternating current. And again, if you don't see that, I suggest you go to the very beginning because I go through that in detail. tail. All right, so now, if you look, I've got a lamp.

The internal resistance of the lamp is 50 ohms, like I show you right there. If I apply ohms law, we see that the current flow in this circuit i is 2.4 volts. I'm sorry, 2.4 amps AC. All right? That would be an rms current, because this is an RMS voltage. All right, so it'd be 2.4 amps, AC, and it's an rms current.

And the lamp will light it should light it should be bright. All right. So now let's see. Let's see what happens. All right, let's clear the slide. Okay, so now let's look at this circuit here.

And it's almost the same as this one except what did we do we we placed a coil in there. And what we have here is again we still haven't lamp that has 50 ohm resistance resistance. Okay, we have a coil that has an XML and XML is inductive reactance inductive reactance is the opposition to current flow in an AC circuit. Okay, this R means one ohm, okay and that R is the actual resistance of the coils or the wire that's wound around that inductor. Okay. All right, so now we use Holmes law And I didn't do up there.

But you should know this by now V equals what? I'm sorry, let's, let's scratch that. We're looking for i and i equals what v divided by R. All right, I'm not going to go out and do the math here. We've done it a lot. But what do we have? We've got 120 volts AC.

Divided by the sum of that, that's one 1051 ohms. And when I do my math, I get zero dot One, two amps, AC. Now, just to regress here a bit that's an rms current. Because 120 volts AC unless I stipulate peak or peak to peak, it's assumed to be an RMS voltage. So that would be an rms current. All right.

So now if we look if we compare this circuit with this one down here, okay, up here we got 2.4 amps of AC current that lamps going to light is going to be bright. But look at this. We've got zero dot One, two amps AC. It's actually only 5% of that 2.4 amps 5%. So that lamp may not even light or if it did, it's going to be very, very dim compared to the top one. All right, so let me clear the slide off and I want to mention a couple of more things here.

Okay, obviously we gave you XML here. This would be the formula that I would use to find XML. We didn't give you the value of the coil. We just said okay XML is, is 1000 ohms. All right. And then if you look at this r equals one and then this 50 ohms especially that r equals one, which which I stated was the internal resistance of the coil the coil windings, alright, that's really insignificant compared to the thousand own XML as far as looking at it from an from an AC circuit point of view.

It's very it's it's like point 1% of that it's, it's, it really doesn't affect it much at all. And even this 50 ohms here, that's fazzi would be 100. That 50 ohms would be 5% of 1000 ohms. It contributes a little bit to the current flow, but basically, if you just just to get a ballpark if you went up Just use that XML of 1000 ohms. You would, you know, you would be, you would be not on the money 100%, but you'd be 890 8.9% or 99% of where you want it to be. Okay?

Again, XML is the opposition to AC current flow. Alright, so the other point I'm trying to make is I give you 120 volts AC. But what would be the frequency of that I didn't give you I didn't tell you the frequency. It's assuming that that's unless other ways otherwise stated that would be the voltage from normal line voltage in someone's home in the US and that is what nominal line voltage in the US is 120 volts AC at 60 hertz, or 60 cycles per second. And again, we've gone over So I just want to, I want to point these things out as we go. Alright, so now let's look at, let's look at this, this last part here.

Where on that circuit here, I've got 120 volts, but it's 120 volts DC. And what does the coil do? How does the coil act when it's placed in a DC Circuit? Well, there's no opposition to DC current flow for the most part. So that XML. I mean, if you look at this formula, what's the frequency of DC?

It's zero. So if I go to pi FL, and f is zero, then x sub l is going to be zero. All right? So really that XML has absolutely no effect. In a DC circuit, it's not even in there because it's not an AC current, its direct current. So again, what what takes effect here is basically the 50 ohm resistance in the lamp and then at a very small amount that that one Ohm in the coil resistance.

Alright, one more point I want to make. I'm going to stop, clear the slide and I'm going to expand upon this point. Now, one thing that you need to be careful about, and I'm going to kind of mention it here. All right, this is all wonderful. It's textbook in and basically it's right, it's correct. But from a practical standpoint, especially up here and up here.

All right, I have to make sure that my conductors can carry 2.4 amps. Now I guarantee one thing if you've got 2020 gauge wire, or 24 gauge wire and you do this, well something's gonna smoke, right? It's probably gonna be a couple of couple of strands of that wire. Alright, so one of the things you've got, you've got to make sure that when you're when you're playing especially with, with DC voltage at someone at a high level, okay? If you've got current flowing, you got to make sure that that conductor can handle that current flow. And ideally it should be directed by 50%.

Meaning if I have let's say, Okay, well, you will round this off to three amps if I'm looking. If I've got three amps of current flowing like my conductor, then I want to find a conductor that can handle six amps or greater. All right now That may not always be the case, there may be other considerations, but I need to look at my I need to look at the, the wire gauge and make sure that that can handle that current If not, something is not going to work out nicely. All right, you're going to see a little bit of smoke somewhere. So that's the point I'm trying to make and in and especially on coils, if you're going to start winding your own coils, because I gave you the formula in the previous section A lot of people do. I mean, I've worked in a research and development lab for many, many years.

And if we were working on a circuit that needed a coil, we would we would figure out the the actual physical diameters of that and and wind that coil so I mean it's put it around a pencil or a or a big eraser or, or we we bought some farms and we and we made them so just make sure that The wire that you use or the conductor that you use, and if you've got some current flow, make sure the conductor can handle that. I beat that to death. We're done. We're going on to the next slide. All right, I just put this little circuit up here and I made a little chart. I want to drive make sure I drive this home.

Again, we know that two pi FL is XML. But look at what happens here. Now I've got 100 volts AC, that's going to be constant. But what happens to I when I decrease my frequency now? frequency is down here is 1000 hertz. Okay.

I'm going to have some nominal current. Alright, I'm not going to calculate it. All right, but my current, my current will be some nominal value. What happens as I decrease my frequency, right? What happens? xml does what if f in decreases, XML gets smaller?

Effects Ebell gets smaller, my current increases, increases. And I abbreviated that as I go up this way more current in my coil. What happens again I'm beating it from from the previous slide. What happens more current. If I don't pick a conductor that can handle the current at the lowest frequency Have a problem. So that's the point I'm trying to make.

All right, even though you pick f sub l, for your nominal frequency, you have to look at the circuit and say, okay, is my frequency going to decrease, if my frequency decreases than my XML also decreases and my current goes up. If my current goes up, depending upon the conductor, the conductor that I use for the coil, I can burn that out. The other thing too is my voltage source. As I decrease, XML current goes up, can my voltage source take the increase a lie? Alright, and that's something you need to think about. All right.

All these parameters have to be thought about or your circuit isn't designed properly, or you're going to have an issue. All right, that's the point I'm trying to make. And I don't mean to beat a dead horse to death. But if you're doing some experiments or you're doing some hobbies or just playing around, and you're going to use this for a specific purpose, you need to take those things into consideration because if you using it all of a sudden you may see some smoke anyways, with that said, Maybe I got a little angel here on this one. Let's go on to the clear this off, go on to the next slide. Okay, on this slide here, we want to talk about XML and the and the different criteria and how we can find different components.

So we know that XML equals two pi FL I've done the math 200 hertz, zero dot Three, two Henry's there's my ex Val but Basically, I can find I can play around with the formula. And we know that f equals XL over two pi L L equals x L over two pi f. And therefore, right here I can solve for L, which is one Henry. And I can solve for the frequency which is 159 hertz there. So the point I'm trying to make here is there's going to be some point and we'll see this when I talk about how to design a linear power supply. If we got to find the value of the coil, which is called a choke, they call it a choke because it removes the AC ripple. Okay, you'll see how I can use one of these formulas Actually, this one here, too, determine what value choke I need to put in there.

What value coil So they'll they'll be times when you're, if you're designing a circuit, you need to solve for other than X sub l, you need to solve for F. And you need to solve for L. And I cleaned off the slide and here are my formulas right there. All right. So take a look at them make a mental note and so forth. So what I've done here, is I've given you the following. I want you to find x sub l, find F and find H. And as always, the answers are on the next slide. Okay, here are the answers.

Ah, XML is 15 1570 ohms. f here is 318 hertz and the value of my choke are my inductor is 250. Micro Henry's Alright, so there's the answers to the problems. Again, they'll be some, if you look at all my modules I, I give you additional exercises in the lesson. So look for some PDFs along with the slideshow that you can pull down and I've given you additional problems and the answers. All right, so let's clear this slide off and go on.

Okay, on this slide here we're looking at series and parallel inductive reactance is and how they act as far as being in series. And in parallel. Basically, right there, we've got two of them. They're in series, just like resistors they add up so my total acquisition I'll say Excel T is, is the sum of them and we're showing you two If there was three, we would just add that, but here we got 100 200. Obviously, that's 300 ohms. So the value there, the total value would be 300.

All right, so let's clear the slide off and see what we we do in parallel. All right over here. We use this formula just like the resistor are resistors. I've got two of them in parallel. If I go through that calculation, my value would be 150 ohms. Now again, I've done a math course and we've seen some of the earlier modules, I went through the math, okay, a va there, take a look at them.

I don't at this point, I'm not going to keep going over math. I usually Know that all right, Nuff said. Let's clear the slide and look and look at the next one. All right, I put this one up here because inductance and inductive reactance. Okay, what I say stayed here is pure inductance circuit voltage leads current by 90 degrees. And that's, that's what I'm trying to show you.

I'm trying again, I'm showing you a graphical representation. So voltage leads current by 90 degrees. So if you can see, at zero degrees, where's my voltage, my voltage is at its peak, and my current is at zero. All right? enough if I go to 90 degrees here My voltage is now in there. So you can see that there is a 90 degrees.

Let me see if I can show it right here. I'll go over here there's a 90 degree shift between my voltage and my current and that's what we mean by voltage leads current by 90 degrees. So again, start off at zero. All right, my peak here is at 90. Alright, so there's my voltage because my voltage would be down here. Okay, so we start at the peak, it's 90 degrees, and current is still zero.

So my voltage leads as far as the sine wave is concerned, my voltage leads current by 90 degrees. All right, that's all I want to say. And I think let's go to the next slide, and I think the That's the Yes, it's the end of this, this module. We've got one more to do. And we'll see you over there. Again, on this website, you've got contact information.

You know how to get ahold of me. See in the next module.