# The surface of sunglasses is curved, yet their power is zero. Why?

The sunglass is covered with a black substance so when light rays  fall on the surface of sunglass,they do not actually strike the surface of the lens hence no refraction takes place hence the power is zero

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But howz that possible @Anurag ?

Without light striking the lens how can we see objects???

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Both the surfaces of sun glass are curved and their radii of curvature are equal. Thus , focal length is equal , so they posseses equal power both from inside structure and outside structure.

So the nulify the power . Hence their power is zero.. ( once surface is convex - outersurface , other is concave-inside surface) Hope u understood..

Cheers!! Thumbs up plz...

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