Question

Which of the following statements is/are true?
Which of the following statements is/are true?

♡A convex lens has -4 dioptre power having a focal length 0.25 m


♡A concave lens has 4 dioptre power having a focal length 0.25 m


♡A concave lens has – 4 dioptre having a focal 0.25 m


♡
A convex lens has 4 dioptre power having a focal length 0.25 m​

Answer 1

Explanation:

We know that

$\color{violet} \boxed{power ,p= \frac{1}{focal \: length} }$

$1. \: = \frac{1}{0.25}$

$\implies \: 4 \: diopter$

Hence this statement is false.

$2. - \frac{1}{0.25}$

$\implies \: - 4 \: diopter$

Hence this statement is false.

$3. \: - \frac{1}{0.25}$

$\implies - 4 \: diopter$

Hence this statement is true.

$4. \: \frac{1}{0.25}$

$\implies \: 4 \: diopter$

Hence this statement is true.