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Name: Tiffany and Victoria
Status: student
Age: 15
Location: N/A
Country: N/A
Date: 11/30/2003


Question:
When we were refracting light through liquids, we were able to produce a spectrum using baby oil, however, it was not as vibrant as the two we produced using water and vinegar. What properties of the oil caused this? We are guessing it is the density of the oil.


Replies:
Tiffany,

Your results depend on the refractive index of the liquid -- the way light rays bend as they pass from air into and back out of the liquid. Try the experiment with a clear cooking oil. Also, you might try pouring some of the liquids into a transparent drinking glass and then leaning a drinking straw in the glass. Look in from the top and through the side of the glass to see how much the straw "appears" to be bent. What you see is an illustration of the liquid's refractive index.

Regards,
ProfHoff 757


The refractive index of water for the sodium D line (the usual optical wavelength used) is about 1.333, for decane it is 1.409 so at first glance one might expect that octane would "bend" the light more. However, you also have to take into account the index of refraction of the container, because the light path is air/container/solution/container/air. Water and vinegar should behave similarly since vinegar is only 5% acetic acid (index of refraction = 1.370). The index of refraction of the container changes the path length that the light travels. The larger the differences in index of refraction between the various substances the "more brilliant" the spectrum should appear. The classic example is air/diamond vs. air/glass.

Vince Calder



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