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Physics33. Geometric OpticsRefraction Of Light

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