Question

A person with myopic eyes is not able to see objects beyond 1.25m. The power of
the lens to correct the defect is
is
a)+ 0:8D

b)+ 1:0D

c)- 0:8D

d) – 1:0D
​

Answer 1

Given:

• Myopic eyes
• Focal length (f) = 1.25m

To find:

• Power of the lens.

Method:

$\sf{Power = \frac{1}{Focal \: length} } \\ \implies \frac{1}{ - 1.25} \\ = - 0.8 \: D$

Therefore, Power = -0.8D

The lens used is Concave lens.

Since the person has myopic eyes, Here, we have taken Focal length as negative. So the power also becomes negative.

Additional information:

1. Power is described as the ability of convergence or divergence of a lens.
2. Concave lens has negative power.
3. Convex lens has positive power.
4. People with myopia wear concave lens.
5. People with Hypermetropia wear Convex lens.