Hey guys. In this video we're going to be talking about how to charge objects so let's get to it. First they're going to be two basic materials you're going to encounter in physics these are conductors and insulators, what a conductor is, it's a material that allows charges to move within it, an insulator is a material that doesn't allow charges to move within it, metals are good conductors, they're a very, very common example of a conductor plastics are good insulators and they too are very, very common examples of insulators. Remember this, okay? A lot of times a question is going to be phrased, a metal blah, blah blah or a plastic blah, blah blah and it's going to be up to you to remember that a metal is a conductor and a plastic is an insulator, okay? So, just remember that. Now, you're going to see this in a laboratory, you're going to see it on your textbook your professor is going to explain this in class because everybody does this example, you can charge a rod by rubbing it with fur, okay? The friction of rubbing two object together strips electrons from one object and gives it to another, okay? The two most common charging scenarios are a fur being rubbed on a plastic rod which will produce a negative charge on the rod and fur on a glass rod which will produce a positive charge on the rod, okay? This is just because this is very, very commonly presented in all the material that you are going to come across but this is no big deal. Now, something that is absolutely universal, this is always true, this is super critical to remember is that like charges repel and unlike charges attract, okay? We all know that opposites attract and in physics, this is also true, okay? Likes repel opposites attract, okay? This is super, super important to commit this to memory because this is an absolutely universal law, okay? Now, one of the main things we're going to talk about in this video is a process known as polarization, okay? Polarization is a separation of charges that results in no net charge okay? How does this work? Well, first let's look at how polarization works in a conductor. So, let's pretend that we have a metal bowl, okay? Inside of this conductor the charges are just evenly distributed however they want to be, let's say we have four negative that are just chillin wherever and for positive charges hanging out, okay? This is an initially neutral conductor because we have the same number of negative charges as we have positive charges. Remember, there is no imbalance there's no charge, okay? Now, we're going to bring a positively charged rod near our conductor, what's going to happen,? Well, remember, that opposites attract so the negative charge is going to accumulate near that positively charged rod and like charges repel. So, positive charge is going to accumulate on the opposite side however we still have 4 negative charges and we still have 4 positive charges, we didn't gain any negatives, we didn't lose it and negatives, nothing changed. So, our object is still neutral, okay? This is a key fact about polarization that we result in no net charge, okay? Now, insulators is going to be very similar but with one key difference, charges can actually move in insulators so we need to look at this at the atomic level. Alright, so instead of just looking at 8 random charges, let's look at 4 atoms within our insulator. Now, these electrons are chillin wherever they feel like, there's nothing to particularly point them in one direction. So, here we have the nucleus and an electron just hanging out, here we have a nucleus and an electron hanging out, here we have a nucleus and an electron hanging out and, here we have a nucleus and an electron hanging out and there's no particular reason why they're in this configuration they're just randomly positioned, okay? Now, what happens when I bring the positively charged rod? Well, now the electrons are going to be pulled towards that positively charged rod they're going to want to hang out as close that positive charge draw as possible. So, what happens all of the atoms orient themselves so that the negative charge, that electron is as close to the positive charge is can be however our initially neutral material, in this case an insulator is still neutral, okay? We did not charge it.
Lastly, we want to talk about conduction, okay? Conduction, conduction is a separate process from polarization that does result in net charge and it does through, it does so through physical contact, okay? That's very important, let's consider an initially neutral conductor, okay? In this case we can say this conductor has 4 electrons or 4 negative charges that are just chillin 4 positive charges that are hanging out inter dispersed, okay? Those same 4 are here, what happens though, when I actually contact our metal ball with the rod, what happens when there's contact? Now, we have the ability or these positive charges, I should say, have the ability to sort of jump ship and get on to our conductor, when I then pull the rod away those positive charges are stuck on our conductor they can't go anywhere, what we've effectively done now is we have 4 negative charges in 4, sorry, 6 positive charges there is now an imbalance in positive and negative charges and we've resulted in a charged object. Alright, thanks for watching.