hi it's Mr Anderson and this is AP Physics Essentials 007 it's on positive and negative charges imagine I take a balloon that doesn't have a charge and I rub it on my head I'm now giving it a charge so I can move it up to something neutral like a wall and if I let it go it'll just stay there now imagine if I take another balloon and I charge that in a similar manner it should have the same charge as the balloon and so if I hold it up next to it and let it go what's going to happen it'll actually be repelled by that object and so scientists speculated there are two types of charges and we call those positive and negative charges and so an electric charge can be positive or negative if we have a neutral object it's going to have an equal amount of each of those different charges but if it's a charged object like a balloon then it's going to have differences in the number of electric charges that it has if it's a negatively charged object it's going to have more of than negative charges and if it's a positively charged object it's going to have more of the positives now let's say I bring two objects next to each other that have different charges what's going to happen there will be an attractive force between the two but if we take two objects that have the same charge and bring them next to each other that could be both positive or both negative they're going to repel each other now why did the balloon stick to the wall if the wall didn't have a charge I hadn't done anything to it well if you move a charge up to a neutral object what it can do is it can polarize that object it can move some of the charges to one end and what it does is create a somewhat charged object so an electric charge can either be positive or negative and so if we're looking at a neutral object how many of those charges are we going to have in that object an equal amount of each now let's say we take a charged object a charged object like that balloon uh what are we going to have we're going to have more of a positive charge if it's a positively charged uh object or if it's a negatively charged object we're going to have more of than negative charges inside it now let's say we take two neutral objects so two balloons that we haven't charged and we move them right next to each other what's going to happen if we let them go nothing's going to happen there's going to be no attraction between the two because the charges are equally distributed let's say we take two objects that have opposite charge so the one on the left has a negative charge one on the right is going to have a positive charge if I let these go what's going to happen there'll be an attractive force between the two Opposites Attract let's say we take two objects have the same charge and move them next to each other and in this case they both have negative charges what'll happen when I Let Go they're going to push away from each other same thing if they're both positive if I let them go they're going to move away from each other now let's say we take a charged object so that's the one on the left and then we have a neutral object that's going to be the one on the right watch carefully what happens as these two come together so as I move the charged object towards the neutral object what it's doing is it's polarizing those charges it's moving the negative charges farther away why because they're being repelled by these negative charges the positive charges are moving towards it and so now there's an attraction between this polarized um what used to be neutral object and so pH makes a wonderful simulation that kind of walks you through that so what we've got uh here's the address down below and I'll put a link in the video description as well so what I'm going to do is take a balloon and I can move that balloon around and if I let it go it just stays where it is but let's say I want to charge it what I can do is I can rub it on a sweater like this and now I'm in applying a charge to that balloon so when I let it go it's going to go right over to the sweater and so if we move it next to the wall and let it go it'll stay there but if I get it close to the sweater then it's going to be attracted and so let's reset this whole thing and look at the charges now so you can see that all these objects are now neutral they have equal amounts of charge but as I rub it on the sweater what I'm really doing is I'm pulling those negative charges off the sweater and now they're on the balloon so now that balloon is a negatively charged object and the sweater is a positive charged object so if I let it go it moves right next to it now watch what happens when I move it next to the wall you can see it's polarizing this neutral object of the wall so I'm not transferring charges but if I move it next to it it's attracted let's get two balloons now and remove the wall so let me add negative charges on this green balloon right here and now let me add more negative charges on this Yellow Balloon what's going to happen well as I move that balloon next to the other balloon these are leg charges and so you can see see that they're repelling each other and it eventually would like to go back to that sweater okay so did you learn the following to explain a two charge model of electric charge again if it's a neutral object we're going to have equal amounts of each of those two different charges did you learn that the distribution of those charges tells us if the object is going to be positively charged or negatively you can see this would be a negatively charged object here and then finally did you learn to explain how the polarization of electric charge or separation of that charge and a neutral object can lead to an attraction so we have an attractive Force here between a charged balloon and what used to be a neutral wall I hope so and I hope that was helpful