June 11, 2015, 715004754 Rev. A
Page 16
Wavelength
The refractive index of a medium has a specific value that changes with the
wavelength of the incident light beam. The 2414 RI detector uses monochromatic
light at a fixed wavelength, so the effect of different wavelengths of light on RI is not
discussed in this guide.
Density
The density of the medium also affects its RI. At a fixed wavelength, the relationship
between the density of a medium and its RI is generally, but not necessarily, linear.
The most important of the factors that affect the density of a medium are:
• composition
• temperature
• pressure
The following figure illustrates the effect of density on the RI of two solutions. The
refractive index of a sucrose solution changes linearly with concentration over this
range of compositions, but a methanol solution exhibits a nonlinear region between
concentrations of 45 and 55%.
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