Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: Rowman on 24/05/2010 09:30:02

Title: How is density related to refractive index?
Post by: Rowman on 24/05/2010 09:30:02

Rowman asked the Naked Scientists:
   
How does density affect the refractive index of a liquid?

What do you think?

Title: How is density related to refractive index?
Post by: graham.d on 24/05/2010 15:52:56

Density is only a factor but I think it is fair to say that the refractive index will correlate with density. In interstellar space the gas and ion density is very low but the greater the density, the higher the refractive index. This is used to estimate the distances of pulsars by measuring the arrival time dispersion (with wavelength) of the emitted pulse.

Title: How is density related to refractive index?
Post by: Bored chemist on 24/05/2010 20:45:11

If you take a liquid like water and warm it up it will expand. The density will fall, and so will the refractive index.
If you put it under great pressure the density will rise, and so will the refractive index.
In these cases the refractive index is very closely related with density. The same is true for a gas like air- compressing it raises the refractive index.
For any particular material the relation between density and refractive index is very clear and nearly linear.
Also, if you look at a number of liquids like alcohol, water and ether the denser liquids often have higher refractive indexes.
However, there are other dense liquids with relatively low refractive indexes and also, there are refrangent liquids that are not particularly dense.


BTW, Tommya300, if you don't know what the answer is, just how useful is your post?
A drop of soap changes the surface tension enormously, but hardly affects  the density.
Also refraction has nothing to do with surface tension.