The power of convex lens of focal length 20 cm is

To calculate the power of a convex lens of focal length 20 cm, we can use the formula:

Power (P) = 1 / focal length (f)

where the focal length is measured in meters.

Converting the focal length of 20 cm to meters, we get:

f = 20 cm = 0.2 m

Using the formula above, we can find the power:

P = 1 / 0.2 m = 5 diopters (D)

Therefore, the power of the convex lens of focal length 20 cm is 5 diopters.