Question

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

Also explain how you get

Answer 1

Answer :-

• (a) A convex lens has 4 diopter power having a focal length 0.25 m

Explanation :-

• P = 1/f
• Power of lens = 1/focal length
• 4 = 1/(0.25)
• 4 = 4

↪ And its is positive +'ve.

↪ The power of a concave and convex lens is negative and positive respectively.

↪ Since the remaining options are incorrect.

Answer 2

Answer:

A concave lens has -4 diopter power having a focal length 0.25 m.

Explanation:

Also explain how you get