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Ray Diagrams for Convex Mirrors

Patrick Ford
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Hey, guys, In this video, we're gonna talk about Ray diagrams for convex mirrors. We already saw them for con cave mirrors. Now we want to see what they look like for the opposite shaped mirrors. All right, let's get to it. While a con cave mirror converges light as we saw when initially column ated light enters a con cave mirror It all comes closer together. Ah, convex mirror will diverge light When light reflects off of a convex mirror, it spreads apart. It doesn't come closer together. That means that the light will never focus. Okay, I cannot emphasize this enough off of a convex mirror. You will never, ever get convergence of light. It will always be divergent. However, if you were looking at this light because your brain is stupid for some reason, you on li see lines. You only see light as traveling in a straight line. So to your brains this line this ray and this ray and this ray this ray this ray and this ray all appear toe have come from a point where they focused. This is known as an apparent focus. There is an apparent focusing of light or an apparent convergence and your brain cannot tell the difference. Okay, so when you look at light coming off of this convex mirror, it appears tohave focused at this point. Okay, this focus, while it's not riel, is often simply referred to as the focus anyway, even though it's technically an apparent focus. And we can define a focal length just like we did before, which is the distance from the apex, too. The apparent focus. Okay, now, to draw Ray diagrams for convex mirrors once again, you need to draw two of the three lines. Thes rules are basically the same, but slightly different because the focus is on the other side of the mirror. So a lot a lion draw a parallel to the axis is then reflected off of the mirror away from the focus. Okay. Ah, line towards the focus is it reflects off of the mirror, parallel to the central axis and finally aligned to the apex of the mirror is reflected at the same incident angle. So the third line is the same. The third rule for Ray diagrams is the same. The first two are very similar, but slightly different in how you apply them because the focus is on the opposite side of the mirror. Let's see what I mean. I'm gonna minimize myself. So we have an unobstructed view of this image when light comes off oven object a convex American also form an image, which is what we're about to see. I cannot stress this enough, Though this image is not actually a really image. It's not really, because light never convergence. Let's see what I mean by this. I'm gonna draw the first type of Ray, which is gonna be parallel to the central axis and then reflected off of the mirror in the direction away from the focus. So you see that green line? The reflected Ray follows that green line as if it was leaving the focus. Okay, now the second line goes towards the focus. Okay, If I were to continue this, it would look like it was going towards the focus. I don't wanna have that right now. Okay? But that's what I mean by towards the focus. And then it's reflected off of the mirror parallel to the central axis. But notice something when you see this Ray, it appears tohave come straight across from the other side of the mirror, right? So there appears to be a focus. There is an apparent image. This image is not riel. This image is not there because the light never actually converge, is there? But it sure does appear to our brains like it's there now. I'm going to draw how we always draw images as just being an arrow that points from the central access to the focus. So this would be upright because it's above the horizontal axis. Okay, since this light appears to converge to our brains, this looks identical to any other image. This is known as a virtual image or an apparent image. It's not riel. It's just virtual. And in this case, the images upright right, The apparent focus point. The apparent convergence of light occurs above the central axis. So the images upright. OK, but these images air. Not really. They are virtual images, but to our eyes they appear to be riel. Okay, let's do a quick example. Where would the image reformed for an object of focal length away from the surface of a convex mirror? So I'm just gonna use the first Ray diagram. The first Ray which is parallel to the central axis. Okay? And then directed away from the focus. Okay, lets whenever you are drawing these lines, you need to continue them on the other side like this. So you know where the light appears to have intersected. The second one is towards the focus and then off of the mirror, parallel to the central axis. So that's towards the focus and then off of the mirror, parallel to the central axis. Whoops. I need to complete this. So you see, right here we have an A parents convergence of light, which is known as a virtual image, and it will appear inside off the focus of the convex mirror. Okay, that wraps up this discussion on ray diagrams for convex mirrors. Thanks for watching guys.