24. Electric Force & Field; Gauss' Law
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Hey, guys. So in this video, we're gonna talk about how charges actually move from one place to another. We talked about electric charges, but you're gonna need to know how they move from one place to another. There's a couple of conceptual points were covered in this video, so electricity, the definition of that word electricity is basically the movements of electrons or electric charges. So inside of objects, it's the electrons that move, not the protons. And so in electrostatic in electricity, the kind of materials that will cover have two different types. You'll run into conductors or insulate er's, and it's your job to know what those with the properties of conductors and insulators do. So conductors basically conduct electricity, and they do that by allowing electrons and electric charges to move around inside of them. So, for instance, metals like copper, aluminum and things like that are very, very conducive to electricity. It's very easy for the electrons inside of the atoms to move around, whereas insulate er's, on the other hand, do not allow electrons and charge is to move. An example of that is like plastics and rubber, so it has to do the actual atoms themselves in the molecules that allows for the electron's to move from one place to another. So how do we actually move charges from one object to another? Well, scientists, When they were working with this stuff 100 years hundreds hundreds of years ago, they found that if you rub objects together, it basically transfers electric charge from one object to another. So, for instance, if they grabbed for and a plastic rod maybe 100 years ago. But the rod requires some kind of charge, and it would either attract or repel certain objects. But if they grabbed for in a glass rod, it would require the different charge like a positive charge and do different things. So the one thing I want you to remember about these positive and negative charges is that like charges repel and unlike charges attract, you've probably heard of the phrase opposites attract things like that that comes from this. So like charges repel each other and, unlike charges, actually want to meet together and attract each other. So let's look at Oakey Way that we can separate or move charges from one place to another inside of an object that's called polarization. What polarization means is polarization is a separation of charges that results in no net charge. So this object here, let's say we have a conductor. We know that inside of conductor, the electrons are able to move. They can freely move. So let's take a look at this conductor here. I've got these atoms. They're just positives and negatives over here. But I've got four atoms of protons and you know of positive charges and electric charge and negative charges. Wow. So this conductor is actually a neutral conductor, so it has the same amount of protons and electrons. So we've got a neutral conductor and let's see what happens when you bring a positive Lee charged Rod close to it. It's not touching it, but it's close enough to it. So what happens is in conductors, the electrons are able to move, and the way that it works is that the electrons essentially want to attract to the positive charges because they're opposites. So the electrons here that are just randomly distributed around the the conductor will start to pile up here on the left hand side, whereas the protons will basically or not, the protons the positive charges will start to go away towards the other side of the object. Now, I wanna be careful here because again I said that protons don't move. So these positive charges are not protons. They're not the same exact thing. But what happens is effectively the electrons will start to push up against the atoms in the left hand side to become negatively charged. And then the ones on the right hand side will become positively charged. So still, in any case, we have the same number of electrons and the same number of protons. So this conductor is still electrically neutral, and that's how it works in conductors. But in insulators, it's a little bit difference. So we know that in Insulate er's electrons cannot move so in insulators, the way polarization works is you still have an electorally if we have an electrically neutral conductor, so we have equal number of positive and negative charges. If you were to bring a glass rod that's close to this thing now the electrons can't pile up on the left side like they did in conductors. Instead, what happens is in these insulators, the atoms themselves at the atomic level will start to rearrange, so you'll start to have the negative charges go to the left and the positive charges go to the right. So what happens is you'll have these these kinds of arrangements here, where you have these positive and negative charges inside of the atoms themselves. That will start to line up in such a way where the positive charges are on the right side, the negative charges on the right, on the left side. And so you have the polarization of the atoms. So in this case, the electrons were not able to move around. But the atoms themselves will polarize in such a way that the negative charges will attract towards the glass rod this way and repel. So I want to point out also that if this was a negatively charged Rod instead of a positively charged rod, all of this stuff would be the opposite. So you have positive charges and left like negative charges on the right, and this would just be flipped. So that's just a different way that could happen if you have a negatively charged rotting. So the other way that you could move charges is by a process known as conduction. So conduction is an actual transfer of charges through physical contact. So that's important thing. I want you to know conduction conduction requires contact. And so conduction also happens in conductors on Lee because again and insulators, you can't have electrons moving around in there. So if you have an electrically neutral conductor like we do here now, instead of bringing the glass rod, that's positively charged so that it's like just hovering above it, but not actually touching it. You're physically going to make contact with the conductor. And what happens is now all of these electrons will start to jump ship, and they basically go onto the glass rod and start to distribute because they wanna be attracted towards the positive charges. What you're left with over here on the actual conductor is maybe a few, you know, electric or a few negative charges, but mostly positive charges. So now what happens is when you remove the glass rod, right and take away those negative charges instead of them coming back. You have basically a net electric charge here. In this case, it was positive, but the result is that you've now created a net charged conductor. So the difference between polarization, which we covered up here and conduction, is that this actually results in a net charge. So again, I just want to reiterate if this was a negatively charged rod instead of a positive charge, Rod, everything would be the opposite. So you have a negatively charged thing because these electrons over here would start to transfer over, so it just be the opposite. Let me know if you guys have any questions. That's it for this video.