 So, first of all, let's talk about right hand rule questions. Stephen, you had a question that you thought I had accidentally done the wrong answer on what number? Oh, you showed it to me. There was two answers? Find it. Because I want to bring that to people's attention, but I don't remember what question it was. Where? Here? There's two answers? I don't think there is. Let me see. Let's go check my answer key. Mr. Dewick, answer key. Answer key. So, right hand rule questions, number seven. I circled two answers. That would be silly of me, but I was doing this in a hurry. No? Because that's wrong. That's right. That's right. That's right. That's wrong. That's wrong. That's right. That's wrong. The only one that has two correct answers is B. That's how I always do these chart questions. I go down the first chart, yes, yes, no, no. I go down the second half of the chart, yes, no, yes, no. Hey, what's the correct answer? I've circled the wrong answer so many times doing that. You should pull it and put it in this chart. It's also going to be 20. Oh, you don't know why? Okay, that I can explain. Okay. So, in this particular question, which way are the negative charges moving at the very beginning, Stephen, to the left? Problem is, we don't use the right hand rule for negative charges. We only use it for positive charges. So, negative charges moving to the left is the same as positive charges moving which way? To the right. Point your thumb to the right. Point your thumb to the right. Magnetic field. What do those X's mean? Magnetic field is into the page. Which way will the negatives also get forced? Both the positives and the negatives will get forced up. In fact, in this particular example, if I can go find that question, what's going to happen is, I'll show you, I'll even draw on it a little bit. So, here's my right hand rule questions. Number seven, right here. The positives would get forced upwards. The negatives would get forced upwards. They would then bubble over and bubble over. What you're actually doing is you're magnetically mixing this solution. You would get a little convection current going this way and a little convection current going this way, except I can't call it a convection current because it's not heat. It's magnetism causing it, but it would be stirring it. Okay, I hope that answered it. Maybe sort of kind of. Four, right here. At first, I didn't realize this was a question, and I typed this up in a hurry last year in OneNote, and OneNote doesn't show you page splits, so I had to guess. Little bit wrong. Almost close. Anyways, what's the direction of the magnetic field directly above a horizontal wire? So, here is my horizontal wire. It's carrying current to the east, and now what I'm going to do is I'm going to put a compass above it, so I have to kind of visualize, and sorry for those of you who are watching this at home, but you guys here, I would point my current to the east, right above my wire, right above my wire. Which way are my fingers pointing? I think here, based on my top view where this is northeast, southwest, I think my fingers end up pointing that way above the wire, which I guess would be south, I guess. Try to remember, this is a question from like about 15 years ago. The graphics are better now. This question probably would no longer make it onto the provincial, but back when they were actually hand-typing provincial exams, they kept the graphics to a minimum. Now, fingers, is that okay? Any others from the right-hand rule assignment, did you guys like this one here, number 13, right above number 14? How many of you have seen the movie, Honey, I Shrunk the Kids, okay? Here is how you could use magnetic fields to shrink something. Which way is the current moving at the top? Put your thumbs to the left. Which way is the magnetic field? At the top, which way is the force? That way. Ah, which way is the current moving at the bottom to the right, which, ah, this thing would actually get compressed, shrinking, it would contract. Very cool. Remember which one, Stephen? 15? Okay, this is the right kind of using principles of physics right to explain type of a question you may expect to see. Also, it's an electron, okay? Moving at a high speed enters a magnetic field. A proton traveling at the same speed then enters the magnetic field. First of all, Stephen, if an electron gets deflected downwards, which way will a proton get deflected? Up. Why? Opposite charges. So I would say no, no, no. The answer right now is R, S, or T. Okay? The real question is, would it get deflected in the same radius, a smaller radius, or a bigger radius? Well, the magnetic force is pushing it in a circle. The magnetic force is QVB, and the circular force is MV squared over R. Hey, a V cancels, kind of cool. Let's get the R by itself, shall we? The radius is equal to, R moves up, QB moves down, MV over QB. Now, both the electron and the proton are entering the same magnetic field, so that won't change the radius. Both the electron and the proton have the same charge, 1.6 times 10 to negative 19, so that won't change the radius. Both the electron and the proton have the same speed, so that won't change the radius. Do an electron and a proton have the same mass? Which one's heavier? So proton, bigger mass, what can you tell me about the radius then? Gotta be. Those are the types of using principles of physics questions, right, to explain, where they'll give you another situation and say, now what would happen to the radius? And it's either going to change the charge, change the mass, change the speed, change the magnetic field, or whatever. Those are great. Well, that's a great one. Okay? Or the idea of different charges having different deflections or different current directions having different deflections. Those are right hand rule stuff is great using principles of physics right to explain questions. Any others on the right hand rule assignment? Then we'll go look at the regular review, but right, those are good? Okay. So now let's move back to my handy-dandy-schmandy tutorial. And from the review, any of these that you're wondering about right now that you've looked at and you've got no idea how the heck you got that, because your homework was the quiz and the review. Number what? Number one? I just got to, there, I can get this now, quick. Number one? In which diagram would the external magnetic field cause two current carrying wires to move towards each other? I think what it's saying, Alyssa, which of these would cause the left wire to move right? The right wire to move left. I'm going to look at all of the left wire ones first, then I'll look at all of the right wire ones. So if I look at the left wire here, the current is traveling which way? So I point my thumb up the page. Which way is the external magnetic field into the page? You know what? That would push it that way. Nope. Wouldn't move it towards, right? Let's try B, magnetic field, sorry, current up the page, magnetic field out of the page. Ooh, this would push it to the, I'm already thinking B. Let's try C, current up, magnetic field to the right. Well, that would push it inwards, but that's not going to push it, right? This one, I can't bend my hand that way, so my palm is pointing into the page. There now it is. D, out of the page. You know what? Can't be that one. I could convince myself, but I'm pretty sure the answer has to be B. Oh heck, just for giggles. Let's try this current as well. So down the page is the current, out of the page is the magnetic field. Ah, this would experience a force that way, and love will happen. They'll meet, and romance will bloom. They're attracted to each other. Nice right hand rule. A little bit of a twist. You got to do it twice. Oh, good. But cool. Okay. Question two. We're worried. Number one and number two suggest people didn't try it. No, maybe not. Be optimistic, Mr. Doock. Ah, this is a cathode ray tube. Okay. First of all, I got to figure out how to fit this all in one page so I can copy it. Let's try. Well, that'll work. We want to deflect this upwards, because it says in order to move the beam to position P, I guess it's hitting here. We want to have the net force upwards. Okay. Now remember in my right hand rule, the force is my palm. So I'm going to work my way backwards, but I'm going to start out with my palm pointing up, and I have to stand up to do this one. So I'll talk really loud so the mic still picks it up. Sorry. I'm not mad at any of you. I just want to make sure the tutorial picks it up. Palm up, because I know the force has to be up. Okay. Which way is the electron moving this way towards you? We don't do electrons. Which way is the proton moving that way? So palm up points your thumb that way. Which way do I want a magnetic field? I want the magnetic field pointing to the left. Okay. I'm going to make a little note. I need the magnetic field pointing to the left. Which of these could give me a magnetic field pointing to the left? Now we're going to have to use our solenoid rule. If I use my right hand rule for solenoids, I imagine holding the solenoid. So if I imagine holding this guy, the WX solenoid, I would either hold it like that, or like that, but regardless, my thumb is either pointing up or down, not left. So I don't think I can get a left magnetic field from a vertical solenoid. Uh-uh, uh, no, no, yes, yes. What's the correct current direction? Now I know magnetic fields point from what to what? North to south. So if I want the magnetic field pointing to the left right here, I want it pointing like that. I think I want a north pole here and the south pole here so the magnetic field points from north. Ah, I saw Kelvin hold his hand up and he said, oh, the current is traveling in direction, my fingers are curling over the top, I think direction Y, yes, yes, no, and Stephen, I always do that, so now I know the answer is C. Oh, if the answer was right here, so it would still be the same solenoid, I think, but it would be opposite current direction Z. You would want a magnetic field to the right, which would mean a north pole there and a south pole here because if you had a south pole right there, magnetic fields always point from what to what? North to south, to south, but let me get rid of that and put the north pole back so that when people print this, they don't freak out, okay? I think you folks are over-complicating some of this. You can really step back and if you're careful, it's not too bad. I'm going to do number three if we're going to continue the trend, but, okay. By the way, number three, I like nice combination of everything. I'm giving you the, it's moving in a circle as a twist instead of saying find the radius, I'm saying find the magnetic field. Ooh, and then I tell you it's from a solenoid, so now that you know the magnetic field, tell me something about the solenoid. That's almost a combination of the whole unit. There's going to be one question on your test that combines using a solenoid, b equals mu naught n i over l, and the right hand rule f c f. There's going to be one question where we combine voltage and electrostatics from a couple of units ago to get a speed, to get a radius. There's going to be nice combination questions. Number what, Matt? Sorry? Oh, cool. Oh, I can't fit it again. You guys are asking me all the big questions. I'm going to do number eight. Well, no, I need to clip it anyways, Mr. Durek. So, okay, zoom to page level, and then we're going to go, boom, clip. And I hope this resolution is good enough that you can still read it. You know the questions, so you can read it even though it's a bit blurry, right? Okay. It says a rectangular loop is suspended by a spring scale between the poles. The loop is that much wide by that much high. Okay. As the current is varied, in fact, as the current increases, what happens to the force on the scale? What that means, my friend, I think is that the magnetic force is down, okay? I think the force is down because it looks like as you jack up the current, more and more and more and more is pulling down. All right. Part one says, what is the weight in newtons of the loop? What you would need to do, Matt, is do a line of best fit with a ruler. Unfortunately, I have to freehand mine because I can't do a ruler very good on my screen. You know what the weight in newtons is when there's no magnetic force? And if magnetic force on a wire is that, when is there no magnetic force when the current is, you know what the y-intercept is your weight in newtons? About 1.5. Does that make sense? A more interesting question is probably going to ask me something about the slope. There is a part B. Is there not? Part B. Part B and a part C. Oh, cool. Let's make those bigger. What is the slope of the best fit line? Go rise over run. I would probably use this point and this point. Make sure you're taking points, Matt, from your line, not the dots. Don't use that dot even though it's a nice dot. If it's not on your line, don't use it. So my rise is going to be, I'm eyeballing it here, from 2 to 5, 3 over. And my run is going to be 6, 1, 5. I'm getting a slope of about 0.6. 0.6 what? Newtons per amp C. What's the magnitude of the magnetic field? What letter is it here? Get it by itself. B equals force divided by current times L. Now here's what's interesting. What do I measure force in? What do I measure current in? I think these two numbers work out to 0.6. Ah, that's why they wanted me to do the slope. I think this is really going to be 0.6 divided by L. Which L? The length of wire in the magnetic field, I think. Which L? That's why they gave me the 0.6 meters. That's why they gave me that. Those slide dogs, look at them. Look at that. I think it's going to be 0.6 divided by 0.6. Good gosh. Did they try and set up a magnetic field of 1 Tesla? That would be very nice of them. Now we've done some rough slopes. So now let me check the actual answer key that I did. My answer might be a little bit off. What number was that, Matt? Oh, 0.06. Did I read the distance wrong? 0.6 meters wide. You know what? Oh, I remember this question. It got tossed. What does it say right there? What does it say right there? This one got tossed. They missed that typo. So if you use that, you'll get an answer closer to 10, not 1, like 8.3, which is close to 10. And that's if you use a point from the graph, or you could use f over i, which actually turns out to be the slope and plug that in, which give you 0.6, which give you 10. So there's a typo on this one. I remember this now. That and that. I still left it on my review because the rest of the concept is so nice in terms of reviewing slope and graphing and being clever with units. Because when you do divide the slope, it is rise over run. It's units over unit. And that is newtons over current. That is force over current. Ah. Is that OK? I explained that all right. Oh, and then just for giggles, I wanted to see if I could actually figure out which way the current was going. Well, if I wanted to go down, I want the force to be down. Magnetic field this way. I said, oh, I guess the current would be flowing that way for what it's worth. It has to be. How do I know the magnetic field is this way? Because all magnetic fields Kelvin always go from what to what? North to south. Magnetic field has to be coming towards me, right? So we'll put it all together. And it is tough, Charles, because it's three-dimensional pictures on a flat piece of paper. I know. And you may notice this is why I haven't tried to draw a single one of these. Ain't going to happen. Next, what number? 11. Cool. Same kind of idea, actually, as the one that Matt just asked, but taking it to another extension. Number 11, Stephen, it says the tension is reduced when we turn the current on. What does reduced mean? Gets bigger or gets smaller? OK, you need to know that. What does reduced mean, Kelvin? Gets smaller. What that means is the magnetic force must have been up the page to make it less tension on the rope. That means the magnetic force up the page, my palm is going to point up. Which way is the magnetic field? What do those x's mean? Into the page in this piece of wire right here, which way is the current flowing? Which then Leslie also means this way, and then Leslie also means this way, and then Leslie also means this way. I think we would call that no, yes, no. Yeah, it's counterclockwise. Hey, we got half of the answers gone. Does that make sense, Leslie? Because it said reduced, I know the force is up, and in my right hand rule, palm is the force. So I pointed my palm up. I know my magnetic field is into the page. My thumb always tells me the current or the moving particle. So my thumb says the current in the section of wire that's in the magnetic field is that. How big? Well, the magnetic force on a wire. So I guess I equals f divided by blah. How big is the magnetic force? What's the tension reduced by? That much? 0.04. How big is the magnetic field? That big. How big is the length of wire that's doing the force? Only that chunk right there. 0.15. So when I first did this, I said, OK. I guess there's a current of 0.04 divided by, and this is wrong, by the way, 4.1 amps. And I circled 4.1 amps, and I looked in the back, and I said, huh, it's not 4.1. This would be the current if there was only one wire. How many coils of wire are there in this question? What does it say, sneaky guys? 25 turns of wire, which means if you got 25 wires doing the lifting, you need 25 times less current. The actual current that you need in each little wire is that big. Yes, yes, no, no. I looked this one up. The stats on this question, I think something like 80% of the kids got it wrong. Most of them picked D. They got the 4.1. And they didn't realize 25 turns, and that means 25 times is the wire lifting. You don't need as big a current. So it's all in my question, really. That's a sneaky, cheap one. Next, going once, going twice, 33, 32. And then remind me to tell you which questions I like. You're like, I'm well, Mr. Goodwill. I like some more than others. Oh, great one. This would also be a great variation on the using principles of physics right to explain question. This one here, Alyssa. What path are these charges tracing out, Alyssa? A circle. OK, this is that FB equals FC. I notice one has a smaller radius, and one has a bigger radius, and they're traveling in opposite directions. Let's assume the first charge, charge Y. Let's assume it's positive. If it was positive, which way is it traveling right there? Up and to the right a tiny bit. Point your thumb up and to the right a tiny bit. Which way is the magnetic field? Put your fingers into the page. If it was positive, which way would it get deflected to the left or to the right? Which way did it get deflected to the left or to the right? Ah, it got deflected in that direction. It should have got deflected in that direction. It must be positive. What about Zed? Which way is Zed moving right here down? Let's assume it's positive. Which way is the magnetic field pointing into the page? If it was positive, which way would it get deflected to the? It would get deflected to the right? Is that correct? Which way did it get deflected to the left? So it can't be positive. What must it be? So what can you tell me about the polarity? Same charge or opposite? No, yes, no. Yet by the way, this guy could be negative and this guy could be fine. But all I know is they can't possibly be the same. Which one's bigger? Well, one of these has a smaller radius. It does tell me they're the same mass and they're the same speed. And it's the same magnetic field. I am once again, I just heard Kelvin say it, going to say that equals that. I'm going to say QVB equals MV squared over R. Kelvin, you're correct. I'm going to cancel out of V. And I'm going to get the R by itself. R equals MV over QB. What can you tell me about their masses? What does the question say? They are? So that's not going to change the radius. What about their speeds? What about the magnetic field that they're both in? OK. So if you have a bigger charge, what will happen to your radius? Smaller. Y must have a bigger charge because it has a smaller radius. Y is not smaller than Z. Y is not smaller than Z. Y is bigger than Z. Y is bigger than Z. Stephen, what's the correct answer? D. Isn't it nice? This is the right-hand rule stuff that I'm throwing at you on your test. Very conceptual. In fact, on the multiple choice, although there's going to be some math, a lot of the questions don't matter. I shouldn't have given up the magnets and they're doing the important stuff. No, because it's not like I put the lesson online as a video or anything. Alternatively, what you're really saying is, Mr. Dewick, you shouldn't have overestimated our maturity. Lesson learned, I'll never do it again. You're saying the magnets possess a certain type of, dare I say it, magnetism? Mr. Dewick, I find the magnets fairly attractive. Oh, OK. I didn't find them very repulsive. Sure enough. Yeah, we'd keep going for a while, and they'll get funnier the later the day goes. But right now, we better stop. Otherwise, funny will be good, teaching will be gone. Next, sensing a pause. Look at the review. Here are questions I like. Let's see. By the way, you'll notice this unit, how many equations actually? Three and a half. I mean, I guess technically that's two separate ones. I'll call it one and a half. Three and a half, basically. Mostly conceptual. Questions that I like. Oh, I'm blanking. I think there is a, I want to say I think there's a cathode ray tube question, but you know what? I think maybe it's on the next test because these overlap, so I can't remember. Anyhow, definitely something like 3A. Something moving in a circle, you better believe you're gonna go FC equals FB, and then solve for either the radius or the mass or the charge, or in this case, the magnetic field, but FC equals FB. Probably something like number five is a good conceptual right-hand rule question. By the way, the answer, number five is a bit obscure. Number five, the answer is D because you would not get a decreasing spiral radius. The radius would be constant because if the radius equals, what was it, MV over QB, the mass of the electron hasn't changed, its speed hasn't changed, its charge hasn't changed, the magnetic field doesn't change. It should be a circle, not a getting smaller spiral. But so some kind of though, hey, which of these is the correct path question, I think is fair game. Something like number seven, there you go. I like that. First, I ask you to calculate the magnetic field, instead of just giving it to you. And then I ask for the radius. That's a little more interesting. And, oh, incidentally, really almost combined the entire unit. We already did eight. Eight is nice as a graphing review mat, but I can't remember if I put a graphing question on this one. Definitely gonna be some kind of magnetic field lines question. So something like number nine, magnetic field lines always point from what to what. So any magnetic field lines here that are pointing from south to north are a problem. And this one's a bit more obvious. I guess this would be, well here, pointing from north to north, uh-uh, right? This is okay, but I'm pretty sure it would be symmetrical. I think I'd be looking at D, I think. Can't be C, north to north. Hang on, let me look here. Wouldn't D on the right side? Oh, you know what? Yeah, you're right, it can't be D. It's gotta be B. North to south, north repels. Yeah, B, I hope I circle B on this. Sorry, because wouldn't these north ones get attracted to the south? I don't know, I was looking for a symmetrical one for some reason. Okay, definitely gonna be some kind of a right-hand rule current carrying wire, number 10. 12 is good. Well, 12B using principles of physics explained the path. I don't think that's your using principles as a physics right to explain, but 12A, find the radius, sure. Again, a magnetic field lines diagram like 13 totally. Oh, apparently 14 was also on your right-hand rules review. I think it's nerdily cool, but some application of right-hand rule. Yeah, I don't think I put a cathode ray tube on this test, next test I think. 17 is a nice conceptual figure out which way you're gonna get a solenoid magnetic field direction. Again, something like 21, finding a right-hand rule for a current carrying wire. 23, absolutely gonna ask you to find, I'm either gonna say, here's a solenoid, tell me the magnetic field, or as a nice twist, I'll tell you the magnetic field and tell me what current would we need, or how many windings would we need, or I was gonna say, or what's the permeability of free space, but no, that's a constant. 4, 5, 10, 10, 8, 7, that'd be a pretty easy one to solve for, because it's 4, 5, 10, 10, 8, 7. So like 25 is good. Right-hand rule stuff, 26 is great. I'm looking now for written questions with a twist. So 28, this idea of when it's moving, what a charge is moving in a circle, when FB equals FC as a part two to a question saying, what if I change one of the parameters? What if there's electrons of proton? Or what if I double the charge, or double the mass, or something? 29, find the magnetic force of direction, absolutely, but that'll probably be a multiple choice, because there's a written that's kind of blue. 31 is a solenoid. 32, 33, oh, this would also be a nice twist on a using principles of physics right to explain. Number 33, simply saying, okay, if you wanna double the radius, what do you have to do with the velocity? Is the velocity squared or not? I can't remember, I have to look at the equation. Or what would happen if you double the velocity? What would happen to the radius? So also, or what would happen if you double the charge? Mix of matching that R equals MV over QB, I think was the equation, okay? By the way, most common mistake is kids cross multiply wrong. So instead of R equals MV over QB, you get R equals QB over MV. They're getting reciprocals of everything, which is the problem. So just be careful when you cross multiply. Ooh, I love number 34, because here, instead of telling you the velocity, the speed, I'm making you calculate it, Justin, from electrostatics by going potential energy equals kinetic energy, QV equals a half MV squared. I like that, nice review. I think we can, oh, now we're on scholarship questions. Which probably means that I added this question at the very end for a very, very good reason after the first year that I handed these out because maybe, I'll let you think about why, I might have added that. Can't get liquid, not much, liquid, not much. Like I'll be honest, number 34, to me, should not be a scholarship. They're giving you a voltage, so you should be able to calculate the speed because they told you the charge and once you know that, you should be able to solve for M because it's moving in a circle. I'm a little surprised that this was a scholarship question. Let me make sure there wasn't a weird twist to that one. 34, no, not 34. Oh, old 34. This was actually very similar to, I think it was number nine that you guys asked me from the homework where I said, I sort of like this, but we're gonna cross multiplying and doing a bunch of stuff. So now I take that back and I will say, okay, fair enough, maybe this is a scholarship. Well, we found V, we found V, we plugged V in and did a bunch of stuff. Okay, fine, I'll live with that. Oh, and you guys got the correction on number five, apparently, that the answer is D. Is that on your actual answers at the back? Yes, I fixed it on yours, okay. So that's some hints. Any more, you would like me to go over any, anyone that I said I liked that you're going, aye, vague, Charles, I love to. And this is one of the few things that I can draw. And proud I am, when Microsoft was here, they actually videotaped me doing that to an empty classroom. They wanted that little as their voice over. I was like, wow, cool. Solenoid, okay. So here's a solenoid. I usually draw a rectangle as my base and here's my battery, my current source. And Charles, I'm going to go to the right underneath, which means I'm coming over the top like this with those funky S's. So I think what you wanted to do is go over the right hand rule for a solenoid, is that correct? Okay, so they'll give you some kind of a picture, probably better than this hand-drawn one, to be honest. But what I want to do is I imagine holding the solenoid in my hand, I'm going to curl my fingers in the direction of the current through the wires, which means I better label this. It looks like the current is going underneath, which means it's coming over the top downwards. Is it not? If I say the current is going this way, it's going up underneath, so over the top downwards, downwards, downwards, downwards. So I have to hold the solenoid like this. I can't possibly hold it like that because now my fingers would be curling over the top away from me instead of curling over the top towards me, is that okay? Okay, hold it like that and your thumb is the north pole. This is the south pole. Sorry, what's opposite? Your thumb points north, okay? Now, outside the magnetic field look like this. In this direction from north to south, north to south, north to south, north to south, north to south. Inside the solenoid, actually the magnetic field would be to the right, it would sort of look like it was going from south to north. It's not, it's a continuous magnetic field. It just means if you stop right here, that's also a south pole compared to that being a north pole. Trust me, it's still, but it works. Is that okay? Yeah? There's your right hand solenoid rule. I don't, if you've got a good handle on the right hand rules, no pun intended. Handle, handle on the, right, all right. If you got a good handle on the right hand rules and you've done the review, you won't see any surprises. On the multiple choice, a lot of it is gonna be, oh, instead of finding F, if I tell you F, find I from Bill or find V from QVB. On the written, I believe there's three questions. One is gonna be a charge moving in a radius. One is gonna be like, oh, a wire going through a magnetic field. What's the force and something to do with that? And one is gonna be, oh, solenoid, calculating the magnetic field. And then I think, there's gonna be two different versions of the test. In one of the versions, you're calculating the magnetic field and then using it to find a radius, what's it's gonna move into. And in the other one, I can't remember that. I'll go to copy these on Saturday. Anything else? Yeah? 25. I don't know, let me get there first. 25. This one? Yeah. I don't know, let's find out. Three distances. And I think I said to you, they love to do that. Otherwise, this unit's really too easy. Nope. So you said, I know that the force on a magnetic wire, on a conducting wire in a magnetic field is Bill. What part of this wire is inside the magnetic field? That chunk. What part of this wire is experiencing the force then? That chunk. So what am I gonna use for my length? That chunk. Why'd they give me that to put one more wrong answer here? Oh, and if the force is up the page, palm up, magnetic field into the page, which weighs my thumb pointing, the current in that wire must be to the right. Gotta be. So, yes, no, yes, no. And what do they want me to find? Current I equals F over F, what was the force? There it is, I covered it up with my calculator. 1.6 divided by bracket 0.65 times 0.22, 11.2, no, no, yes, yes, C, yep. 13, 1, 3, 14, 1, 4. The one after 13? That one? Sure can. Oh, too far. Oh, sure. I did this one earlier in class, but I'll do it again. Because it's so cool. This is also on your right hand rules assignment. There was some overlap. This one? This is cool. At the top of this loop, right there, which way is the current traveling? Put your thumb to the left. Which way is the magnetic field? Which way is your palm pointing? This is going to get pushed this way. Now, what about down here? Which way is the current traveling? It's going to get pushed that way. But what about right here? Which way is the current traveling? It's going to get pushed that way. What about right here? Can we push that way? You know what? This loop is going to, and what's the fancy word that they use for contract? Honey, I shrunk the loop. Have you guys ever been to Disney and seen the Honey, I shrunk the audience show? Very cool. Especially when the mice start running into the audience and everyone starts screaming because little things start scratching your legs. Pause for a second. Back to live now, told my little story. Any more you want me to go over? If not, who would like a copy of this? I can print it if you want me to. I mean, it's mostly cut and paste, but anybody want a copy? One? Can I do what? Sure can. Then I'll do a copy. 31. Can't remember what that one was. Oh, cool. Cathode ray tube. Yeah. How televisions used to work? Stupid plasma. Greg, you laugh. But honestly, six years ago, this was so cool because I could explain to kids how televisions work. Like it was, wow, that's relevant. That's what my computer monitor is doing. Yes. Now it's like, I don't know how my iPod works. There's no tube back there. That's fine. Technology changing. I think what I need to do, first of all, Matt, electron coming towards me, proton traveling away. Right there. I need to figure out which way this is gonna create a magnetic field. It says this is positive and current flows from positive to negative. I am going to argue in this solenoid that I would hold it like this, not like this. Is that okay? So which way is north, sorry for those of you at home. Like what? Can't see. I would hold it, I think, with my thumb pointing up. Which means this is the north pole. This is the south pole. Magnetic fields always point from what to what? Huh? Don't do that. North to south. Say that again. Just to reinforce, magnetic fields always point from what to what? To what? That means right here, the magnetic field is to south. It's up. That electron is going through a magnetic field pointing up. So now we can right hand rule. Electron coming towards me. Proton traveling away from me. Magnetic field pointing right where the electron is up. Direction four. Is that right? Yep, right? Electron, a proton, electron that way. Magnetic field up the page. Which way is my palm pointing? Right on there, it's direction four. Right? Just curious, do you guys find it easier if I do it on the board than you imagine that's your paper? Or if I do it on my screen here and that? Okay, so I'll remember what I'm teaching to turn around. It's okay? Unfortunately, I only have a few cathode rate tube questions. I'm guessing because they're so graphics intensive, they don't show up very often and I was only able to find a few in the old exams. And this level of graphics is well beyond my skill level, unfortunately. And it's even beyond my skill level to take one of these and get a new question out. Some of these, a lot of your quizzes, I've liquid papered or whited over a number and just changed the number. This one, 3D diagrams like that don't work so well. Still cool. Oh, the current balance? No, but I would have no problem putting a wire in a solenoid and saying calculate the force, build. Oh, I didn't tell you the B. Oh, it's a solenoid, calculate the B. I would have no problem doing that, okay? But I don't think I'd ask you to specifically break down the current balance. I wanted to show you some applications. The application that is part of the learning outcomes though is the cathode rate tube and the electric motor. Those two you do need to know, but I'm gonna be hammering the electric motor next unit, the one that we just started. I always show it in the first unit, but we're gonna be looking at a generator next unit, which is an electric motor in reverse. So we'll be reinforcing that. Okay, so I'm gonna go like this first of all. Turn off.