 Now let's look at magnetic forces, particularly the right hand rule. And the right hand rule is used to find the direction for the B force. And to do this, you have to use your right hand, but different parts of your hand represent different quantities. So your thumb represents the velocity, your fingers represent the magnetic field, and your palm represents then the direction of the force. And that would be the force on a positive charge. If you happen to have a negative charge, well, that throws the force in the opposite direction, which would be like the back of your hand. Now here's a cartoon example. In this particular example, they're showing the velocity, again lined with your thumb, to the right. The magnetic field is with your fingers pointed up towards the top of your page. And then in that case, the palm is out of the page. Now it's very important to keep your hand nice and stiff like this with the fingers pointing straight up, not in any other direction. When we start describing directions, you're going to often see some standard direction descriptions. For example, right and left. Well, that's going to show us horizontally if we're moving back or forth across the paper. When you see just up or down, up represents towards the top of your page, and down represents towards the bottom of the page. And that's true whether you're working on a screen that's sitting flat in front of you, or if you're talking about a piece of paper laying flat down on a table. The other directions we have, you've got to start thinking three-dimensionally, because it's into and out of the page. So if you imagine you're holding your paper up in front of you like a screen, into the page, it goes away from you into the page. Out of the page would come out of the page towards your body. Here's an example with a hand. Take just a moment here and see if you can figure out which quantities are in which directions. Well, we start with velocity, and that's represented by your thumb. So this one is showing you velocity upwards. Then you've got your magnetic field, which is represented by your fingers. And so those are pointed to the right in this case. So which direction is your force? That goes with the palm of your hand, and that would be then pushing into the screen. Now note, when you actually start trying to align your hand, it's generally easier to align your fingers with the B field first, and then rotate your hand around your wrist, keeping your fingers in the same direction, until your thumb is aligned with the velocity. Now in this next set of slides here, I've got some videos where it shows someone placing their hand in various different positions. It's a good idea if you sort of practice along. It's kind of quick, so you might need to re-rind and re-watch parts of the video. Did you get all of those? Remember, the person is bringing their hand in, aligning the fingers with the B field first, and then rotating the hand to align the thumb with the velocity. You'll need more practice with the right hand rule, but this is a good introduction to it.