Okay, in this section here, we're going to measure current, and we're going to use my little lab power supply that I pulled out of the Trashman. You remember the one where the 12 volts is in 12 volts, but anyways, we're going to use that and what I've done here is give you an illustration. All right, and I kind of want to have you focusing on on these terms, all right, when we measure voltage, the meter is across the components. So if you look here, my meter is in cross are in parallel with the resistor Okay, so I measure voltage, a cross or in parallel with the component. When measuring current, the meter is in series with the component, just like I show you here, notice, what I've done is I've broken Well, I haven't broken up I have taken this media lead right there. And I've disconnected this lead, and I've attached over here, just like I'm showing you there.

So if you look, let's look at how current flow current flows this way. Here, up through the meter, through the resistor and down. Okay, let me let me stop here and erase this and we'll do current flow on The voltage side here and you'll see what I mean. So if we look at current flow this way, we have current flow through the resistor. And we actually have a current flow through the meter. All right, so the meter is across are in parallel with the component.

And when I'm measuring current, the meter is in series with the component, that's the point I'm trying to drive home here. Okay, that's what I want to drive home. Now over here, and here, I've just given you a schematic, or an electrical schematic representation of the same thing. Here's my resistor. Here's my battery. My schematic equivalent of a volt meter, it's across the resistor.

Over here is my voltage source. Here's my resistor and you can see my meter is in series. Ah, it would be like this. I didn't put the polarity here, but that's would be the polarity. Let me do it over here also. Alright, now, we're going to measure current.

So this is out of the little manual that I enclosed on this lecture. So less than 200 milliamp hours read tests lead to milliamps or more than 200 milli ampere tests lead to 10 a jack black test lead to common jack set the rotary switch to micro amp is milliamp hours, or 10 amp position and press Select button to select the DCA measurement mode. Alrighty We'll see that when we go and when we we actually measure current. All right. And what I've done here is I've calculated the current for you should be a review current equals voltage divided by resistance. If I've got 11 and a half volts DC and I've got a 510 ohm resistor, I do my math, it should be 22 and a half milliamp hours and look at what we got power.

All right, I just want to make you're aware of this. Okay? When I have a resistor across my voltage source, alright. Remember, back in the days when we did basic circuit analysis, and we talked about the value, the water draining of the component, well, mate, we're going to hit that a little bit. So can knock that home a little bit. we're calculating 258 milliwatts.

All right, and we're going to use a quad a watt resistor which happens to be 250 milliwatts. Okay, so a quarter watt let me put that here. Quite a watt equals 250 milliwatts. I should have put that in there. I didn't actually, let me stop here clear off the screen and I'll put that in. So I clear the slide off and I add 250 milliwatts equals a quad a watt.

When I do my math, I get 258 milliwatts, just a tad over. So we're going to look at that a little bit. Okay. All right. Okay. All right.

So let's do it. I'm going to stop here. I'm going to go over and we're going to start with Doing these, this lab and we'll take it from there, see over there. Okay, before we go on, I also wanted to mention that we're also going to do current, we're going to measure current through the five volt section of this, this power supply. Alright, so I put them both up here. Again, what I'm measuring my 12 are which is actually 11 and a half volts.

This is what we get is my power consumption. When I go through my math and I do my calculations, I find out that this resistor here, will dissipate, dissipate 258 milli watts aquata watt is 250 milliwatts max. So we'll see what happens there. And now I'm back over here at my, my five volts section. So if I do My math to solve for current, we know previously that voltage divided by resistance equals 9.8 milliamp hours here, okay? That would be the current flow through this 510 ohm resistor.

And again, when I when I calculate my power, it would be 9.8 milliamps times five volts. I go through the math. It's 49 milliwatts. And that's more than adequate because we know that a quite a watt resistor, which is what the sizes on both of these can dissipate, 250 milliwatts. All right. So let's see what goes on.

Again, I wanted to put this in here. So now what we're going to do is we're going to set up our lab, and I'm going to go through that and after I do that, we have what we call a follow along lap. We will have batteries and resistors that you can follow along with and make sure you understand this and you will actually do the hands on and quite honestly yes it's these are simple law labs to start off with to get you familiar with what we need to do, but I can assure you as we go along they'll get a little bit more complicated. All right, so don't say wow, this is easy. Yes, these are easy. We're going to build upon these.

Alright, with that said, let's go on. Okay, real quick. I added this here. This is the color coding of the resistor. In other words, the band's first band is green. Second band is brown.

Third band is black, last band fourth, which is gold. And that would give me 510. Oh, Okay, 510 ohms All right, I just want to throw that out there. I I mean, that's been so long ago that we've talked about that I just kind of want to drive that home. Also, if that seems a little fuzzy, go back, um, I think it's understanding voltage, current and resistance, which is the first a second part of my course. And I think it'll give you a refresher.

All right, let's finally go on. Okay, we're gonna measure rock current right now, and I've got my little power supply, power supply computer power supply that we use in the last last one or the last section. And remember, we've got this little connector here in the middle here. Is my ground. And then I have a, I'm gonna say 11.5 volts DC, and this is five volts. And what I usually do is, before I do anything, I usually measure the voltage coming out of my terminal, and that's something that I do you know.

So I'm going to turn the meter on. And notice again it on this particular meter, it comes up on AC. So I'm going to do hit the selector and I'm going to get a DC voltage. I'm going to take my meter leads. I gotta take my meter leads, and I'm going to go in doesn't matter. I'm going to measure the five volt first.

I could have measured the other one if I wanted to. And I believe it's off. So let me turn it on. There we go. My power Supply I just turned it on. So we getting 5.12 volts.

Alright, so now I'm going to measure my 11 volts or 11 and a half volts approximately. And I'm getting 11.40 I so we're good enough. I again, oh, ideally 12, but it's 11.4. The two inner conductors are common. All right, they're both ground and the red one is plus five, I can use either one of these black conductors. If you notice that I that I moved my conductor and the last one, I just did that to make it a little bit easier to get my, my red meter lead over here, that's all.

So we're going to measure current now and we're going to measure milliamp hours. So if you look All right, I've got micro hampers milliamp person tampers. Alright, so when I measure current, and we've we've done the calculations on here on the previous slide, we noticed that it was approximately 9.8 milliamp hours, okay, I use five volts DC, and I use the 510 ohm resistor, okay? It may be a little bit, my, my current measurement may be a little bit higher because we actually measured 5.2. Alright, so it'll be a little bit higher, but we'll be in that. That 9.8 10 milliamp range, I'm sure.

And how I do this is remember we put our meter in series. So that's what I'm going to do now. So I'm going to take my Well first of all, I'm going to take and move my function switch to milliamp ers and then notice I'm still on a C AC current. So I got to do my selector. And now I'm on DC milliamp hours. And you can see it says Ma, they're familiar campers.

And I'm going to get a clip lead right here. Let's let's put this right there so you guys can see it. And let me move this down a little bit. Let's move that over here. All right. And so I'm going to connect to my negative terminal.

And I think I've got a good connection there. We'll see. And then I've got the other end here. And I am going to connect that to my negative meter lead on my common meter lead. All right. All right.

So now I've got my black meter lead connected over here. All right. And my White meter lead is going to ground my black meter leaders connected to the other, the other side of the resistor right here, I and there's my black meter lead let me just move that up a little bit. And now we have my red meter lead and I'm going to go into the five volt and see we are measuring 10 milliamp hours again, I right here is my black mirror, my my comment online on my power supply follow this white lead down and we're on that side of the resistor. Okay, the other side of the resistor I have my green media lead on you Going into my black meter lead right there. And then my right meter lead is connected to the five volt source of this power supply.

My current meter is in series with the resistor and I'm measuring 10.18 milliamp hours, which would make sense because the calculated value of this was 9.8 milliamp hours. We did the calculations with five volts, we're actually getting a little bit more voltage. So it's actually 5.2 which would, which would raise the current a bit so we're good. And the other thing I'm going to do now is we're going to leave it where it is. And I'm going to take my meter probe and I'm going to go across My 11.5 voltage, and ideally, my current should go up. Let's see if it does.

And indeed it does. We're measuring 22.1 milliamp hours. All right. Okay, so we're going to stop here. And we'll pick it up. What I'm going to talk about next time is on the next section where we measure current, about the wattage rating a little bit and we'll pick it up there.

Okay, we're going to put a quarter we've got a quarter watt here. Now, we're going to put a half squat and I believe I've got a two watt resistor in there. We're going to put that in there. And we'll see what the differences Alright, see you on the next one. Bye.