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What happens at the boundary with light refraction?

  1. Jan 1, 2016 #1
    There is something I have been wondering about with refraction. There have been many explanations of why the light bends. However, it still does not feel intuitive. The question I have is with how light enters the clear object. Is it proven that light indeed enters at an angle that is instantly changed. In other words, does the light bend instantly to the new angle or is there a small curve around the entry point. It would be easier to draw what I am talking about, but I am new to this.

    What I am interested in finding is a highly magnified image of the bending of light as it is being refracted. Tried to find a decent image on the web but there is too much other clutter.
    There is potential for light to be bent with a very small curve, but there it would be hard to see. Would love to hear of any experiments about this topic. Most likely it is something that was proven long ago.
    Thank you,
  2. jcsd
  3. Jan 1, 2016 #2


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    If you imagine larger waves it might be easier to picture. For instance, with microwaves entering a block of wax at an angle, we can imagine the electric field lines being distorted by the interface over a depth of something like half a wavelength, before finally arriving at the new angle.
  4. Jan 1, 2016 #3
    Thank you tech99,
    This is a very quick turn. Does it matter what the wavelength is? Is it always roughly half of the wavelength?
    Also, are you aware of any experiments about this that are available online?
  5. Jan 2, 2016 #4


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    No. As long as the wavelength in question can actually propagate through both media, the same thing happens. This link shows the easiest way to think about how it happens. One thing always applies and that is phase continuity across the boundary; you can't suddenly have a jump in the phase of the transmitted wave. So, if the speed in the second medium is less, the wavelength must be less and so the waves emerging from the surface will have to change direction to satisfy this. I suggest you do a search on refraction at an interface and look at all the various versions of the above - perhaps with an animation. It will probably make sense to you when you hit on the one that's appropriate to you. You are very lucky, these days. In the old days, we had just one text book at home with us and, if that explanation didn't happen to help us, we were just floundering around till (and if) the teacher could put us straight. You now have almost infinite variety of presentations of these basic bits of Physics on the Web. Use it as often as you can..
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