Question

why are the sub glasses which have the curved surfaces don't have any power?​

Answer 1

Answer:

Sun glasses have curved surface but their power is zero. Why? Because the inner surface curvature matches the outer surface curvature thus there is no lensing effect. ... It is also quite possible that sunglasses 'lenses' are made of material which is less refractive than that used for regular glasses.

Answer 2

Answer:

"sunglasses"

Explanation:

Because both the surfaces of glasses are equally curved .