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