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Anderson Video - Refraction of Light

Professor Anderson
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<font color="#ffffff">Okay, so the very first one and the practice problem says the following.</font> <font color="#ffffff">It says when a beam of light, originally traveling in air, enters a piece of glass</font> <font color="#ffffff">having an index of refraction of one and a half, it's frequency does what?</font> <font color="#ffffff">So, light going from air to glass,</font> <font color="#ffffff">let's draw a little picture of this thing.</font> <font color="#ffffff">Here's our chunk of glass, here comes our light wave and it's going to head into the glass</font> <font color="#ffffff">and something's going to happen to it, okay. What happens to this light wave?</font> <font color="#ffffff">Well when it's in air, we know that it is traveling at C,</font> <font color="#ffffff">but when it's in the material, what's it traveling at?</font> <font color="#ffffff">V, which is less than C.</font> <font color="#ffffff">Right, V equals c over n. C we know is lambda knot times frequency knot over N,</font> <font color="#ffffff">but now in this material it's going to be some new lambda times F,</font> <font color="#ffffff">and so now you're faced with a choice, right? Is</font> <font color="#ffffff">lambda equal to lambda knot over N, or is f equal to f naught over N.</font> <font color="#ffffff">One of those is true and one of those is false,</font> <font color="#ffffff">and this is what this question is asking about,</font> <font color="#ffffff">it's asking is this one true, or is the frequency not affected.</font> <font color="#ffffff">So, anybody remember which one is affected and which one is not?</font> <font color="#ffffff">The wavelength is the one that's affected, okay.</font> <font color="#ffffff">The wavelength gets shorter and so if we draw this in the</font> <font color="#ffffff">material, we should really draw it with a shorter wavelength.</font> <font color="#ffffff">Okay, and propagating through the material but it still has the exact same frequency.</font> <font color="#ffffff">So we would say that the frequency is in fact unaffected.</font>