Okay, in this section here, we're going to be talking about capacitance. Okay? a capacitor is an energy storage device, meaning it will store voltage and we'll see how that works as we go on. All right, a capacitor have two metal plates, as shown here. All right. There's a dielectric material, which is a type of an insulator between the plates.

All right. So these are my, my graphical representations of a capacitor. All right, and right in the air. Physically when it's manufactured right here, Okay, there's a plate now if you can look at it this one here, all right see the plates while they turn with this knob. All right, but what's in between the plates here to air okay. I believe this one here is a mylar and mylar is a special type of insulating material and when they manufacture these, here are my my leads for my plates right there.

Okay, the the leads are the plates are separated by this mylar material it's in here along with this. This is called the disk capacitor. And that's also has some insulating material in there. All right, and that's what I'm that's what I'm telling you right there. All right. pipes have died.

Dielectric material are air micropayment And I think on the on the next slide here, I list a few more. All right, now here's the deal with a capacitor free electrons cannot flow through the insulator. So therefore, the capacitor holds a charge. I cannot let me say that one more time, I cannot get direct current flow through here. All right. And we'll go into that in a little bit more detail in the upcoming slides.

But right now, a capacitor if I put a capacitor in a DC circuit, it will block DC current. Okay, I can not get current flow. All right. So that's it on this slide. The only other thing that I want to introduce here is make yourself very, very familiar with these symbols of a capacitor here. Let me let me clear up the Slide.

All right, what I want to, what I want to show you is the schematic symbols for a capacitor, right? That's one right there. Alright, notice, this one looks the same, but I've got a little plus there. So that means when that capacitor is placed in a circuit, all right, this lead needs to go to the positive point of the circuit. And if you look here, what they do is, you see this right there? Well, and on on the body of the capacitor, instead of showing a positive, they show a negative.

So obviously, if that's negative, that lead there would have to be positive. So it's got to be placed in correctly into this circuit with the platter polarity observe these are also called electro lytic capacitors. Alright, let me say that one more time electrolytic capacitors Alright, and an electrolytic capacitor is polarized, where it has a negative and positive lead on the body of the capacitor the physical body and we have to observe which way we put it into the circuit. Just a quick little note here. If you have an electrolytic capacitor, and you put it in the wrong way, the capacitor will get damaged. And it could, you could hear a little bit of a pop.

Alright, so just just letting you know that Okay, this one here is is a variable capacitor. Notice with the Arrow through it. All right. And these are all right here, right here. And right there are all schematic symbols for a capacitor. All right.

Let's move on. And let's go to the next slide. All right, now on this slide here, I've drawn a circuit here. And basically what do I have? I've got a battery, which is 15 volts DC. And I've got a capacitor, okay.

And that capacitor has a dielectric as we talked about before, and a dielectric is an insulator. And what I've done for informational purposes, is giving you a little bit of a chart of the more popular or the most common dielectric materials. You can see here, the first one is there. I have four micro in glass paper. polystyrene Pyrex and so forth. And you can go over that.

But they're, they're different materials and they have different characteristics of why we want to put put them in, in as a dielectric on a capacitor. So for now, we'll just leave that there. And the point DEP, the point I want to make here is when I place the capacitor in this circuit, and put voltage across and again, in this case, 15 volts, the voltage across the capacitor will equal the voltage source, okay? And that will be instantaneously The minute I put that capacitor on there, it'll charge up to 15 volts. And if I pull the capacitor out, it'll still hold that 15 volts DC. So again, a capacitor is an energy storage device, it will hold a charge.

All right. Now, one of the points that I want to make on this, and I'm going to clear this slide off here is when I place this capacitor into this circuit, all right, notice I've got my positive polarity here. So if that's positive, this has got to be negative. So if you remember when we talked about circuit theory, and we put that we had resistances in the circuit, and we talked about how our electron flows, does the same thing here. All right. But, so when I place the capacitor in the circuit, I get electron flow here, all right, and if this is negative, All right, we have a surplus of electrons here.

And we have what a shortage of electrons up there. But if the dielectric in between the plates of the capacitor is an insulator, and we know that insulators do not conduct electricity, where do we get the electrons? Well, we really don't. Okay, the electrons are redistributed on the capacitor. So for instance, since I have a surplus of electrons on this side, where do those electrons come from? They come from the top on top of the capacitor flow through the battery.

Battery and get collected on the bottom plate of the capacitor which is then the negative side. So, we redistribute the electrons on a capacitor. Alright. And then think about it. When the capacitor is fully discharged, we have the same amount of electrons on my positive side of the capacitor as I do on my negative side of the capacitor, so the capacitor is discharged. Alright.

Again, when I place my capacitor in a circuit, the capacitor charges to the voltage source instantaneously. All right, where does it get the negative or the electrons it gets it from the positive plate. The capacitor, and basically all they do is redistribute the electrons in a capacitor and that's what I'm telling you right here. All right, they get redistributed. Which brings us down to this equation here. So the charge on the capacitor is Q equal CV, where Q or the charge is in cool ohms.

See is the value of the capacitance measured in ferrets. And V is the voltage across the capacitor. So just just let's look at this and look at this relationship here. Just to get a little bit of an understanding. There's my equation so If I want more charge, and when I say want more charge, that means I want to get more electrons redistributed. Alright.

So in other words, I want to have more electrons in my negative plate than I do on my positive side of the capacitors. So to do that, I need to increase either C, which is the value of the capacitor, or V, which is the voltage across the capacitor. All right. All right. So let's, let's see what I mean. Let me just do a quick, quick problem here.

Okay, well, here's my formula q equals CV. And as we said, capacitors are measured in farads. So one ferret times 10 volts, I have 10 cool Arms. Okay, if I increase the value of the capacitor and make it to keep my voltage the same, I get 20 cool ohms. And over here if I reduce the my value of my capacitor, but increase the voltage across it, I get 20 cool. Um, so it's a relationship right here as a relationship.

And that's, that's the point I want to make here. All right, okay. So, right now, we went over this. And we talked about what's up here. All right, what I've done is we talk about q equals c times v. So what is what is, what is q? q stands for cold.

Cool. What is it cool? Well, remember when we charge this capacitor up, we have a surplus of electrical here and in a shortage of electrons here, and we know from the previous slide the electrons get redistributed. So if I can redistribute this many electrons 6.25 times 10 to the 18th electrons. And if I have a surplus of this number on that plate, I have one colome of charge. All right, one cool oma charge, if I might, if this is two times that.

Then I have two cool ohms a two Q and three times that three cool ohms. If I have a half of that, I have a half a cool if I've got a 10th Now that I've got a 10th of a cool, all right, so that's one column of charge again 6.25 times 10 to the 18th electron. That's a pretty big number, isn't it? Alright. So, we talked about capacitors in the in the previous section, we will talk about this equation. I said that the capacitor was measured in ferrets, well, that's sort of true, but because a ferret is is the area of a ferret would be very, very large.

Our capacitors are measured in micro farads, Pico farads and a micro farad is 10 to the minus six Pico is 10 to the minus 12. All right, so and I give you an example micro farad is abbreviated us, pico farad is that should not be an N that should be a P. Also a capacitors have working voltage ratings. So for instance, I'll give you an example here 47 micro ferrets at 50 volts working volts DC or 50 w VDC working volts DC. What does that mean? That means that not only do I have a rating for the capacitor value for the capacitor in in micro farads, I also have to have a voltage rating. So, if I've got a circuit where when I place that capacitor in there, at some point it'll give me let's say 25 volts across the capacitor I have to make sure that I get a voltage rating ideally that should not equal it should be actually greater.

And the rule of thumb is two times. So if the voltage across the capacitor placing when I place it in the circuit is 25 volts I should I need to get something two times that in this case, that would be 50 w VDC worked in volts DC. So, I need to make sure that the voltage rating I'm placing the fastener in is adequate. All right. Ah, just to add that, let's say I had a capacitor that was 10 microphones. And the circuit voltage was was 20.

But I only had a 35 volt capacitor. Could I place that in there? Yeah, you you could do that. Alright, it's not quite to time. But it's adequate. So it's kind of you got to get a little bit of a feel for that.

However, I can say this. If I have a circuit, and let's say, the voltage rating or the voltage when I placed a capacitor in the circuit is a maximum 20 volts, and I put a five a 10 volt working volt DC capacitor in there, it's going to pop, it's going to blow up, it's going to be damaged. So with that said, Just Just be careful. And again, the point I'm trying to make here is when I when we rate capacitors, we have a value in farad z, the micro farads, a Pico farads. And we also have a working volt DC specification for the capacitor. Alright, Nuff said.

Let's go on.