​The power of a convex lens of focal length 20 cm is ___________. ​

Correct option is B

The correct answer is (B) 5.0 D.

Power of a convex lens

• The power of a lens is its capacity to alter the light that enters it.
• Because a lens with a shorter focal length bends lights more, it has more power.
• The light rays converge toward the principal axis in a convex lens, while the light rays diverge away from the principal axis in a concave lens. Here, $$P=\frac{1}{f}$$​
• The inverse of a lens's focal length (f) in meters (m) is its power.
• A lens's power is measured in m-1. Diopter is another name for this.

Calculations Given,

Convex lens

Focal Length, $$f = 20cm= \frac{20}{100}=0.2m$$​

We know,$$P=\frac{1}{f}$$​

So putting values in formula

$$P=\frac{1}{0.2}=\frac{10}{2}$$​

P= 5.0D