Question

Question 8
Which of the following statements is true?
(a) A convex lens has 4 dioptre power having a focal length 0.25 m.
(b) A convex lens has -4 dioptre power having a focal length -0.25 m.
(c) A concave lens has 4 dioptre power having a focal length 0.25 m.
(d) A concave lens has 4 dioptre power having a focal length -0.25 m.

Answer 1

(a) A convex lens has 4 dioptre power having a focal length 0.25 m.

A convex lens which has focal length 0.25 m, will have power equal to $\frac{1}{f}=\frac{1}{\left(0.25\right)}=4D$