A person got his eyes tested by an optician. The prescription for the spectacle lenses to be made reads :Left eye : +2.50 D Right eye : +2.00 D(a) State whether these lenses are thicker in the middle or at the edges.(b) Which lens bends the light rays more strongly?(c) State whether these spectacle lenses will converge light rays or perge light rays.

 (a) These lenses are thicker at the middle because they have positive power which implies that they are a convex lens. 

(b)  Lens for the left eye bends the light rays more strongly, as it has a shorter focal length. And, we know that the power is inversely proportional to focal length $(P=\frac {1}{f})$. Therefore, a lens of more power has a shorter focal length which is +2.50D in this case.

(c) These spectacles will converge light rays because these are the convex lenses.

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Updated on: 10-Oct-2022

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