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Refraction of light! help

  1. Jan 15, 2007 #1
    i need an explanation for this situation.
    i've inserted an pingpong ball into a glass full with water (the glass is made out of thick glass if it matters somehow?).
    Now what happened is that the half of the ball that is in the water looks much bigger than the half that is not in the water.

    My question is why the ball that is in the water looks so big? how does it connected to light refraction?

    p.s- I added a sketch for you to understand better the situation!


    A reply would be very much appreciated

    Attached Files:

    Last edited: Jan 15, 2007
  2. jcsd
  3. Jan 15, 2007 #2

    Claude Bile

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    The cylindrical shape of the glass+water acts as a lens, magnifying the ball. Lenses cause this magnification because of the way light refracts.

  4. Jan 15, 2007 #3

    Many thanks for your fast reply :)
    Would you mind adding a more detailed explanation or to direct me to website that will explain it more clearer?
  5. Jan 15, 2007 #4


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    Since the water surface is not flat - becuase of the container and other factors. The light is bent into a new path. The light is bent outwards and is spread out.

  6. Jan 15, 2007 #5
  7. Jan 15, 2007 #6


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  8. Jan 16, 2007 #7
    Thanks ranger :)
  9. Jan 16, 2007 #8
    one more question!
    Does the combination of water and cylinder shaped glass creats the effect of cylindrical lens?
  10. Jan 16, 2007 #9
    Anyone want to attempt a QED explanation?
  11. Jan 16, 2007 #10

    Claude Bile

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    Yes, you'll notice that the ball is magnified along the horizontal axis but not the vertical.

  12. Jan 16, 2007 #11
    :rofl: lol. why?
  13. Jan 16, 2007 #12

    Attached Files:

  14. Jan 17, 2007 #13
    I was just curious :uhh:
  15. Jan 17, 2007 #14
    hmm...if light rays are basically refracted further apart, then why don't we get a certain distortion (blind spots)?
  16. Jan 17, 2007 #15
    In this domain, the ray approximation of light is sufficient to understand the image (combined with snell's law of refraction).

    If you wanted, you could try to understand snell's law of refraction. You could do so by switching to wave (rather than ray) optics (combined with knowledge of the wave velocity in various media).

    If you wanted to understand why wave optics is relevent (and why the wave velocities differ among media), you might study classical electrodynamics. In depth. I'm just saying it would be a long time before you understood the physics of your problem well enough to be able (or to need) to use quantum electrodynamics to further improve your understanding.
    Last edited: Jan 17, 2007
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