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Refractive index of different liquids

  1. Dec 12, 2011 #1

    Some of my students are doing an experiment, investigating the refractive index of different liquids such as water, alcohol, syrup (very concentrated sugar solution!), and oil.

    The results that of their experiments seem to be showing that oil has a high refractive index than water and the sugar solution a lower refractive index. We thought at first that the refractive index would be linked to the density of the material. However, with these two liquids seems to be going in the opposite direction, as in, the liquid with the lower density actually has a higher refractive index.

    Can anyone offer some alternative explanation(s) about how different materials affect the speed of light and hence refractive index.


  2. jcsd
  3. Dec 12, 2011 #2
    Optical Density shouldn't be confused with mass/volume density of a substance.
    Your case is a perfect example to explain the above!
  4. Feb 26, 2012 #3
    Thanks - that is kind of what I was thinking - so we want to research optical density. Actually I was thinking how strange it is that different kinds of matter can appear transparent at some wavelengths such as radio and gamma but opaque at visible wavelengths. Are there any instances where light is transparent through at certain material at visible wavelengths but opaque to radio or other waves? I think not, except some materials that are visibly transparent do absorb infrared and UV - hmmm
  5. Feb 26, 2012 #4
    The ionosphere is transparent for visible light but opaque for short radio waves.
  6. Feb 27, 2012 #5


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    Staff: Mentor

    The window of your microwave oven.

    Lead glass gives radiation shielding, but I don't know whether that includes gamma radiation.
    Last edited: Feb 27, 2012
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