Question

A doctor has prescribed a corrective lens of 2.0 D to a person. Which of the following statement/s can be associated with this data?

• A. The corrective lens is of converging nature.
• B. The corrective lens is of diverging nature.
• C. The lens prescribed is used to correct myopia.
• D. The lens prescribed is used to correct hypermetropia.

Answer 1

Answer: (A), (D)

The correct options are
A The corrective lens is of converging nature.
D The lens prescribed is used to correct hypermetropia.

Given: Power of a lens $P=2D$.
Since we know $P=\frac{1}{f\left(inmetre\right)}$
where $f$ is the focal length of the lens in metre.
$f=\frac{1}{P}=\frac{1}{2}=0.5m$
Since focal length is positive, it is a converging (convex) lens.
Convex lens are used to correct hypermetropia which can be seen from the ray diagram.