I got to knew that when light passes through the optical centre, then it bent , but as the lens is very thin , this bent is negligible and thus we neglect it but when other rays passes through the lens(except optical centre) then why does they bent more?lens is thin so why should'nt we neglect it too??

Asked by jgprmr | 17th Jun, 2017, 12:38: AM

Expert Answer:

1) It is true that light incident on the optical centre bends a little but we neglect that bend. The neglection is mainly due to the fact that at optical centre the light is incident normally. That is, it is a normal incidence and we can consider light to exit the lens without bending. At normal incidence light does not bend after refraction.
 
2) At other points on the lens the light is incident at some angle with respect to normal, so that light ray follows the Snell's law and refracts at a particular angle.

Answered by Romal Bhansali | 20th Dec, 2017, 11:51: AM

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