Question
Mon February 27, 2012 By:
 

dispersion is caused by refraction, but not by reflection.why?

Expert Reply
Mon February 27, 2012
 In a darkened room a pencil of light prepared by slit-shaped diaphragms is directed onto a glass prism. The prism is placed on white paper to make the path of the light and its spreading visible. The light finally falls on a tilted piece of white cardboard, showing the spectrum. The spreading is due to the fact that the index of refraction of the glass depends on the wavelength of the light. This dependence of the refractive index on wavelength (or frequency) is called dispersion, and is the source of several beautiful atmospheric colour phenomena, like rainbow etc.
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