6 A thin lens is made in the shape of a disc of thickness d

Last updated: 6/1/2023

6 A thin lens is made in the shape of a disc of thickness d and radius R The refractive index u of material of disc varies with distance r from the centre If parallel beam of light get focused at distance f R from the lens then refractive index at centre of disc is 1 sip 3 r 2df r d f 2 4 F r 2df 2 r