Question

prove that : sin i /sin r = n2/n1

Answer 1

Please refer to the your text book for the proof of snell's law as it is clearly explained in the text book.

Follow the link provided below:

http://www.learnnext.com/nextgurukul/wiki/concept/Andhra-Pradesh/X/Physics/Refraction---Snell-s-Law.htm

Answer 2

Like with reflection, refraction also involves the angles that the incident ray and the refracted ray make with the normal to the surface at the point of refraction. This is called Snell's law.
if we consider two mediums, the angle made by the incident ray is n1sini
similarly, the refracted ray made some angle, that is n2sinr
where, n1 and n2 are two mediums in which light incident and get refracted
equating n1sini= n2sinr
therefore, we get sini/ sinr= n2/ n1