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

Question

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

MyClass24 · Accepted Answer

Soln:

Answer is (a) A convex lens has 4 dioptre power having a focal length 0.25 m
Explanation:
Positive value for focal length indicates convex lens.