 Alright, so if you've seen very many of these videos, you're familiar with the light board setup that we use, the light board that I use to write equations and content on while I'm talking to you. But I do get a lot of questions from students about how exactly this light board works. I've had a couple students even tell me that they're somewhat distracted thinking about how in the world this setup could work, that it sometimes distracts them from being able to focus on the physical chemistry content of the lecture. That's the point of this video is just to briefly describe how this light board setup works, give you a behind the scenes tour of the light board. So the basic idea is pretty simple, it's about like you imagine it is. There's a piece of glass in front of me that I write on. I write equations on the glass. The frame of the glass is surrounded by LED lights that illuminate this fluorescent marker so that it's bright enough to be caught well by the camera. The tricky part, the part you may have wondered about, however, is how is it that when I write on the board, if I write an equation on the board, I'm writing this equation so that it looks fine to me. If you were standing in the room with me on the other side of the glass, the equation would look backwards to you. How is it that this equation in fact doesn't look backwards, it looks forwards to you? The key there is that the camera that's doing the recording is attached to a computer that digitally reverses the image before saving it as a video file. So I can write forwards, you can still read it forwards. And I can demonstrate how that works if we bring in a second camera, one that's not doing the image reversal. So over here is Dallas. Dallas is the videographer that is normally running the cameras and running the computer and doing the edits to make sure that these videos look nice and professional. If Dallas watches me write another equation from this side of the board, this equation is going to look just fine. You'll see me writing it with my right hand because I'm right-handed and everything's fine. But if we have that camera move to the other side of the board, if I write a different equation now, then from the opposite side of the board, that camera is going to show an equation that looks backwards to you. You're going to have a hard time reading this equation. Notice that I'm still writing with my right hand or appears to you that way. And I am writing with my right hand, but the equation looks backwards. If we switch back to the stationary camera, the one that is doing the image reversal, now when I write an equation, now it's going to look fine to you. The difference, however, is that it looks to you like I'm writing with my left hand. So the image has been reversed. It looks to you like I'm writing with my left hand, even though I'm writing with my right hand. So I can illustrate all that one more way if it takes a little more repetition to really make sense. If I hold up something that I haven't written, a printed piece of material that has the text written forward, I can read that just fine. Anyone else in the room with me can read that just fine to you. Through this image-reversed camera, this text is going to appear backwards. And that's because of the image reversal. But if we switch back one more time to Dallas's camera that's not doing the image reversal, then the text on this magazine cover is going to look forward, you can read that just fine. So notice one additional complication about this image reversal is as we talked about, I'm right-handed. I'm holding this pen in my right hand through Dallas's camera. It looks like I'm holding the pen in my right hand. But if we switch back to the stationary camera, that's going to show me as if I'm holding the pen in my left hand, again because of the image reversal. That adds a slight complication when I need to talk about topics that explicitly involve mention of left or right. So for example, when we're talking about chirality or symmetry, if I want to talk about a clockwise rotation or a counterclockwise rotation, if I want to mention a right-hand rule or something like that in order to do a cross-product or a right-handed coordinate system, I have to twist my brain a little bit and be careful to do things with my left hand so that it looks to you as if I'm doing them with my right hand. But if we ignore a few small features like that, everything is very straightforward. I can just write equations the way I'm used to. The camera reverses them. You can read them the way you're used to and everything is a piece of cake. So hopefully that has satisfied those of you who are curious about how this lightboard setup works and it will free your brain up to pay full attention to the physical chemistry topics we talk about. So I'll see you in the next lecture.