Here we have our apparatus for this week's diffraction of myob. This is our light source. You can see it says mercury on the apparatus, but don't believe it because we can change the goals. The rest of this collectively is called the spectrometer. This will be your culminating telescope. The purpose of it is to use the slit in here to narrow down the light source into a fine line. Then theoretically we can focus that in to give us just a focus to be. On the other side here we have our imaging telescope. This is one that you'll actually be looking through. You'll be moving it around to get the measurements on your various lines. Sitting on the rotating stage here we have our prism. You can see it's an equal lateral prism made of glass. Our home today is to find the index of refraction of this as a function of weight. One thing to note on the rotating stage here there are three lines and just so happen to be 60 degrees apart. Those are helpful in centering the earth prism. You can line the corner of the prism up with one of these lines and that will help you get the prism centered which is very important in this life. There are three screws that will be using on the spectrometer to make adjustments. This screw here to the right of the imaging telescope unlocks the imaging scope. Then you can tighten it down to lock the scope. On the other side the left hand side of the imaging telescope. There's another screw that unlocks the ring that has the markings for the degrees. If you unlock that you can rotate the silver ring around to zero out your measurement to wherever you want it to be. The third and final screw that we'll be using is behind the columnating telescope. That one unlocks the stage so that you can rotate the prism. Then tighten it down to lock it in place. There are also a couple other adjustments we can make to align your telescopes. You can use this screw to move the scope left and right. This screw will move the scope up and down. This will help you get your image to where you need it to be so that you can see all of the lines in the spectrum. You can also, once you get your scope roughly where you need it to be, you can do some final just with this screw down here. What this does is just moves the scope relative to the image that you see in very small increments. If you can't quite get exactly on the line, you can lock down your scope and use the final just to get closer. The first step in this experiment is to align your columnating scope with your light source. You want to look through the scope and adjust the width of the slit with this screw until you get as narrowed even as you can that's still relatively bright. At this point, the lights will be off, but just for demonstration purposes, we can do this with the lights on so you can see it better. The next step is to place your prism. You want this center as you possibly can, which is usually accomplished by lining the corners with the lines on the stage. From here, you want to find the spectral lines. Just get down on a level with the prism and look at it with your eyes and then you can swing the scope into place. Then focus in on one single line in the spectral. At this point, we need to find the minimum deviation angle, which is accomplished by locking down your scope and unlocking the stage. You then look through the imagery telescope and rotate the stage. As you do this, you'll see the lines move. If they move one direction and just keep going, you're rotating the wrong way. So if you turn it around and rotate the other way, you'll see that they move one direction, then stop and turn around. The bulkier is to lock down the stage at the point when they turn around. That is our minimum deviation. We'll look through the lens and we'll see these different color lines.