Electric Fields in Conductors

Concept: Electric Fields in Conductors

5m
Video Transcript

Hey guys. In this video we're going to be discussing, what electric fields look like inside conductors, okay? Let's get to it. Just as a refresher remember that charges inside of a conductor are allowed to move, okay? Now, inside a conductor which charges are allowed to move? It's the electrons not, the protons the protons are stuck inside the nuclei and the nuclei in solids are pretty much fixed in position. So, you have these electrons that loosely associate with atoms that are free to sort of jump from atom to atom to atom and move around the conductors. Now, these electrons want to get as far apart as possible because like charges repel. Remember that, as a direct consequence of these electrons pushing as far away from each other as possible the electric field inside the conductor will always be 0 you must remember this, this is one of those Universal things in physics that it will be up to you to remember, that the electric field is always 0 inside of a conductor. Remember this, committed to memory, okay? Now, what I want to talk about is how charges arrange themselves inside of a conductor, let's consider starting with two negative charges, what are those two negative charges going to do? Well, they want to get as far away from each other as possible. So, they're going to jump to opposite ends of this conductor, okay? Now, I drew them outside the conductor but really what they are is on the surface of the conductor. So, they're chilling right here on the surface and they're chilling right here on the surface, okay? What, if I were to add two more electrons, two more negative charges? Well, these are also going to want to be as far away from each other possible but also as far away from the original two as possible. So, they're going to jump up and down. Now, each of them is as far away from the other as possible right, they're along the rim on the surface of this conductor and they're each like 90 degrees apart, if we're looking this, if we're looking at this like a circle? Well, what about more? What if I have four more? There they're gonna go? Where they're going to go? Exactly halfway between each of these negative charges that are already there and now these are always far away from each other as they possibly can be, okay? This is going to hold for however many electrons you want, they want to spread themselves out over the largest possible area, on a conductor, actually on any material, the largest possible area is always going to be the surface area, the outside of that conductor, so the charges are going to spread themselves out evenly on the surface area, on the outside of the conductor and what that leads to, and we'll talk more about this later, is that inside the conductor. So, if I draw a little circle here, representing the inside of the conductor, the electric field is 0, inside the conductor, okay? And remember, this is always true, this is an absolutely universal law, committed to memory. Remember it, okay? Charges always move to the surface, on conductors, okay? Remember this, right here, charges always move to the surface on conductors, let's do an example.

A rectangular conductor with a positive charge Q is placed in a uniform electric field, right? That's what these field lines are, draw the electric field lines and charts distribution of the conductor, okay? First there are no electric field lines inside the conductor, the electric field is 0 inside the conductor, boom done, if it has a positive charge Q, that positive charge just distributes itself an outside of the conductor. So, let's say there's a positive here or a positive here, positive here, here, here, here, here and here, boom done, as simple as that, charge distributes itself on the outside of the conductor, on the surface of the conductor electric field inside the conductor is 0, we're done, okay? That wraps up our discussion on electric fields and conductors, thanks for watching.