Question

A person can see up to 2m .What is the power of the lens he should use to increase his range up to 10m

Answer 1

Hola

Answer is

1/10 - 1/2 = 1/f

1-5/10 = 1/f

-4/10 = 1/f

f = -10/4

f = -2.5 m

Power of a lens is given by 1/f

1/-2.5 = -0.4D