Question

a man used a convex lens of focal length of 20 cm in his spects, the power of this lens is​

Answer 1

Qᴜᴇsᴛɪᴏɴ

a man used a convex lens of focal length of 20 cm in his spects, the power of this lens is

Aɴsᴡᴇʀ

The power of a convex lens is positive and that of a concave lens is negative. Thus a convex lens of focal length 40 cm is said to possess a power of + 2.5 dioptre. similarly the power of a concave lens of focal length 20 cm is 5.0 dioptre

Answer 2

Answer:

5 dioptres...

Explanation:

20 cm = 20/100 m = 1/5 m

power = 1/1/5 = 5d