Physics Mirrors

因此，让我们现在谈论镜子和图像形成，然后才能得到太多，我真的想谈论成为图像的含义。好吧，发生的事情是我们采用一个物体，然后将其放在镜子前，光从那个物体反射出来，然后从镜子上反射，然后重要的是，在光线从镜子上反射出镜子后，光线会发生什么。好吧，这个想法是，有时这种光会反映镜子，然后再次又回来，这意味着它将改革同一形象。它看起来就像它在反射对象时所做的那样，因此，这就是图像的含义，它看起来像一个对象。现在，如果光实际浏览了图像，以使其反射并通过并重新聚集，那么我们将其称为真实。好的，图像是真实的，如果另一方面看起来像是一个图像，实际上，光线根本没有重新召集，那么该图像将被称为虚拟。

我们会发现，如果您仅使用单个镜子或一个镜头，那么真实的图像总是会倒置是朝下的好事。另一方面，如果有一个镜子或单个镜头，则虚拟图像始终是直立或右侧的。然后，当然我们可以放大倍率，始终通过图像与镜子的距离之比除以物体离镜子的距离的比例。好吧，所以让我们用最简单的情况（平面镜子的情况）快速地做到这一点。好吧，飞机镜子是这样的，我们从物体中散发出光线，它只是直接反射，所以有一个。让我们抽出一个，好吧，我从物体上得到了光，然后它只是反射，记住反射角度等于入射角，这样它就可以了。

Now here's the question, are these 2 rays ever going to recombine? Well it certainly doesn't look like it right they're just getting further and further apart. So what would I mean by an image? I mean I stand in front of a plane mirror I see an image, here's the idea, when I stand in front of a plane mirror I see these two light rays but my brain doesn't automatically think about the mirror being there it just says okay there's those two lights rays. So it extrapolates the light rays back as if the mirror wasn't there and so look and it looks like. It looks like the light came from here look at that, same distance behind the mirror as the object was in front of the mirror, same size as the object that's the image. Notice that the image is erect it's right side up and it's the same size and same distance away. So we have a virtual image because the light never actually was here if I go and look behind the mirror I'm not going to see anything there right? Well I'll see a wall okay. So the idea is no light actually came here so virtual erect image, same distance away from the mirror as the object with a magnification of 1 alright which means it's not magnified.

一个lright so let's look at a slightly more complicated cases and these are the cases associated with curved mirrors. But we need to do this kind of carefully, there's 3 major cases the concave mirror 2 cases of that and the convex mirror only 1 case there so that will be nice. Alright let's look at the concave mirror first, alright if the object is far away from the mirror, how far depends on how concave it is, how curved in it is. But if the object is far, let's draw a couple of these rays, let's draw 1 to the vertex alright it's going to reflect off same angle it came in at. Alright and then we'll do 1 straight out so we'll do 1 just like this and it reflects at the same angle it came in at, but remember that angle is measured off of the normal. So I got to draw me a little normal alright and then I got to draw the reflector and look at that, we do have these rays recombining. So this gives us a real image but notice that the real image is inverted okay so this is going to give me real inverted image alright it's going to be closer the magnification will be less than 1 alright and so this is what happens. Now let's think about what will happen if I start moving this object.

It turns out what happens is as the object moves closer and closer and closer to the mirror the image moves further and further and further away. Alright these 2 things will coincide at a distance that's equal to the radius of the circle that this would make if you made a circle it's called the radius of curvature how curvy is it, alright the more flat it is the bigger that radius is. The more curvy it is, the smaller that radius is, so these 2 things will come they'll overlap and then they'll go like this. The image will go off to infinity as the object goes to a certain place in front of the mirror called the focal length. Alright and that will be discussed in more detail in the segment on the lens equation. Alright so what happens if I get closer than the focal length? Well let's see again we'll draw 2 rays, there's one and then let's draw another, draw this one in green. So we'll go straight over and then remember I got to give myself my normal alright and these 2 are actually not, sorry these 2 are actually not going to overlap they're not going to ever recombine alright so I have to continue them backwards to see where my image is.

现在，我的图像在这里更高，虚拟和直立，因此这是虚拟的，直立的。因此，基本上，这个想法是用凹面的镜子，物体在镜子上移动更靠近镜子，我有一个真实的倒置图像，从镜子上移开了2件事，这两个东西短暂重合，大小相同，但其中一个是真实的，对象是对象显然是真实的。图像将是真实的和倒置的，然后一旦对象到达我们在这里的某个点，图像就会熄灭。图像出现在另一侧，现在是虚拟和直立的，随着对象靠近镜子，图像也将靠近镜子。好吧，这是凹的，这是最复杂的情​​况。好吧，现在让我们做一个更轻松的情况，让我们凸出凸的凸面是这样的，然后我再次需要像这样的小正常。好吧，所以有一个让我们再做一个，我们在这里像这样跌倒了。请注意，这2个显然永远不会重组好的，因此这意味着我们有一个虚拟图像，我们可以通过继续这些几何线并查看我们最终得到的东西来确定那是哪里。

我们最终得到了这里发生的一切，因此问题是，这里我们总是有一个勃起的虚拟图像，它远离镜子，而不是对象。在这种情况下，我们总是具有比对象更接近镜子的勃起虚拟图像。例如，这些镜子在商店中非常非常有用，因为所有镜子在1处的放大倍数很小，这意味着，如果您使用这些凸镜之一，您可以看到更多，您可以看到更多，您可以看到整个商店一旦正确，这些凹面镜子就不是这种情况。凹面镜实际上是用来放大事物的，因此这些是关于镜子和图像形成的方式的一些定性想法。