Question

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

1. State whether these lenses are thicker in the middle or at the edges.
2. Which lens bends the light rays more strongly?
3. State whether these spectacle lenses will converge light rays or diverge light rays.

Answer 1

1. These lenses are thicker in the middle because they are convex lenses.
2. Power is inversely proportional to focal length; therefore, a shorter focal length will mean stronger bending. Hence, the lens for the left eye will bend light rays more strongly.
3. These spectacles will converge light rays because a convex lens has positive power.