Question

The power of glass of a person is 0.75 D. What is the nature of the lens (b) what is the focal length of lens?

Answer 1

Step 1

Given data.

Convex lens power = $.75D$

Power is the positive focal length of the lens is positive, a convex lens is used by the person.

Step 2

Relation between focal length and the power

Focal length = 1/power

$$\begin{gathered} f=\frac{1}{power} \\ f=\frac{1}{.75} \\ f=1.33m \end{gathered}$$

Hence the focal length is 1.33 m.