posted by Thaifa .
1. For a particular piece of glass the refractive index for X- rays of wavelength 1.60 X 10^-6 less than unity. At what maximum angle, measured to the surface , must a beam of X-rays strike the glass to undergo total internal reflection?
2 An oil drop of thickness 2.5 x 10^-5cm is on the surface of water in a water tank of area 1square meter. White light which is incident normally is observed through a spectrometer. The spectrum is seen to contain one dark band whose center has a wavelength of 6.5 x 10^-5cm in the air. Find the refractive index of oil.