In 1836 Cauchy gave the following approximate formula to describe the wavelength dependenc...

In 1836 Cauchy gave the following approximate formula to describe the wavelength dependence of refractive index in glass in the visible region of the spectrum

Now (see also Table 12.2)

  n(λ1) = 1.50883 ; n(λ2) = 1.51690 for borosilicate glass

  n(λ1) = 1.45640 ; n(λ2) = 1.46318 for vitreous quartz

where λ1 = 0.6563 μm and λ2 = 0.4861 μm.

(a) Calculate the values of A and B.

(b) Using the Cauchy formula calculate the refractive index at 0.5890 μm and 0.3988 μm and compare with the corresponding experimental values:

(i) (1.51124 and 1.52546) for borosilicate glass and

(ii) (1.45845 and 1.47030) for vitreous quartz.