Question

Which of the following statements is correct? (1)

(a) A convex lens has -2.5 dioptre power having a focal length 0.4m.

(b) A convex lens has 2.5 dioptre power having a focal length 0.4m.

(c) A convex lens has 2.5 dioptre power having a focal length 4cm.

(d) A concave lens has -2.5 dioptre power having a focal length 4cm.​

Answer 1

Answer:

Explanation:

F = 1/P = 1/2.5 = 0.4m = +40cm

Focal length is 40cm and it is a convex lens