Question

A doctor has prescribed corrective lens of power +1.5 D. Find the focal length of the lens. Is the prescribed lens diverging or converging?

Answer 1

Step-by-step explanation:

Power (D) of the given lens = +1.5D

This implies +1.5 = 1/f

or 1/1.5 = f

or 10/15 = f

or +2/3 cm = f

As focal length is positive, hence the following lens is converging (Convex Lens).

Answer 2

$\huge \sf \pink{Solution.}$

Given, power of lens,

P = +1.5 D

It means the lens is convex

As power,

$P = \frac{1}{f(in \: m)}$

So,

$f = \frac{1}{P} = \frac {1}{1.5} = \frac{10}{15} = 0.66 \: m$

$f = 0.66 \times 100 = 66 \: cm$

It is a converging lens because its focal length is

positive.