 Let's take a look at the right hand rule for the force on a current carrying wire. For this video I'm actually using the web camera and an actual right hand, and I've got it set up so that it should look on the screen like a normal right hand. If I take my general rule and here's a nice cartoon one so I can write things out, my thumb represents the direction of the current. So I'll move my thumb in whichever direction the current is going. My fingers, just like our previous rule, represent the magnetic field and then the force, the flat part of my hand, is going to show the direction the force is going. Is it moving up towards out of the page, out of the camera? Am I moving to the left, to the right? Got to remember to flip things around. Now I'm working in a little bit more limited space here, so it's going to look a little strange, but hopefully you can follow along with your own hand. So let's start off with a case where I've got the magnetic field in a region of space moving upwards. If I have a current carrying wire in that region of space, I could have it such that its current is flowing along towards the right. So this is very much like what I had my hand showing before. So again, my fingers are pointed upwards, and then I rotate my hand around until my fingers are still pointed upwards, but now my thumb is pointed off towards the right. In this case, what I see is my force comes up out of my palm, and so that means for this particular case, I've got a force out of the page, screen, whatever you want to refer to that as. If I had one that was moving to the left, then again, my fingers have got to point upwards, and I rotate my hand until my thumb is pointing over towards the left. The palm of my hand is going to push down, and that means for this case, the force would be in to the paper. Okay, let's take another look at another one. Let's say I have a magnetic field which is pointed off towards the left, and I'm going to do a couple of different currents for this one. So for example, I want a current which is pointed towards the right. Now, if I got my fingers over there, physically, my thumb is not going to point all the way over in that direction. It just doesn't bend that way, even being double-jointed, and so we look at this and we realize that the angle between these two particular ones well, that's 180 degrees, and if I go back to my thinking on my formula, the sign of 180 degrees is zero, so this is no force. And again, you have to have the current trying to go across the magnetic field lines, otherwise there's no force. Okay, so let's stick with the same force over here, moving with the magnetic field to the left, and let's say I've got a current moving upwards. Fingers, rotate around to be in that direction, and okay, I got to flip it over so my thumb is going with the current. That's again a case of a force going out. Okay, it's a little hard to follow these on camera, but you keep practicing. Okay, so let's take a look at this magnetic field. Okay, the first thing that you want to remember is that when I see the dots, that means my B field is pointed out towards you. You're seeing the very, very tips of the arrows. So if I've got a magnetic field pointed outwards, I can put my wire anywhere flat along this page, and it's going to be going across the magnetic field lines. So let's try one like this. Okay, so my fingers are going to have to point up towards the camera, and when I've got them pointed towards the camera, I need to have my thumb pointed over here towards the side. It's kind of hard to see, but when you get everything lined up, fingers pointed towards the camera, thumb pointing over here towards the right, then what I see is my force is downwards. Okay, one more question here. Let's say I've got a magnetic field pointed in, and I have got a current pointed upwards. Which direction is the force? Figure this out to collaboratively, together as a class. Fill this one in on your worksheet. We're going to stop the video now, and we'll move on with the next part in just a moment.