Question

A person can see the objects lying between $25cm$ and the $10m$ from his eye. His vision can be corrected by using lens of power:

Answer 1

Step 1: Given

1. The range of vision is from $25cm$ to $10m$
2. Here, a concave lens of focal length $10m$ should be used because a concave lens is used for the correction of myopia, and the focal length must be $10m$ so that he must be able to see the distant objects.

Step 2: Formula used

$Power\left(P\right)=\frac{1}{focallengthinm}$

Step 3: Calculating power

$$\begin{gathered} \Rightarrow P=\frac{1}{-10} \\ \Rightarrow P=-0.1D \end{gathered}$$

Hence, the power of the lens is $-0.1D$.