A person cannot see distinctly objects kept beyond 2m. Which among the

1.	A person cannot see distinctly objects kept beyond 2m. Which among these lens is useful to correct the defect a) – 0.2D b) – 0.5 D c) + 0.2D d) +0.5D?
Answer» The person is suffering from Myopia. The lens is concave and its focal length f = – 2m. P = 1/5 = 1/-2 = -0.5D So to correct the defect concave lens of – 0.5 D power should be used (b).

A person cannot see distinctly objects kept beyond 2m. Which among these lens is useful to correct the defect a) – 0.2D b) – 0.5 D c) + 0.2D d) +0.5D?

Answer»

The person is suffering from Myopia. The lens is concave and its focal length f = – 2m.

P = 1/5 = 1/-2 = -0.5D

So to correct the defect concave lens of

– 0.5 D power should be used (b).