Question

the focal length of a convex lens is 25 cm what is its power.​

Answer 1

Answer:

Power is expressed as the inverse of focal length, where a focal length of 1 meter is equal to one diopter. So a 25 cm. focal length (0.25 meters) has a power of 4 diopters.

Answer 2

Given,

The focal length of a convex lens = 25 cm

To find,

The power of the convex lens.

Solution,

We can simply solve this numerical problem by using the following process:

Mathematically,

Power of a lens

Power of a lens = 1/(focal length of the lens in meters)

Now, the power of the given convex lens

= 1/(focal length of the lens in meters)

= 1/(25 cm) = 1/(0.25 m)

= +4 Diopter = +4 D

Hence, the power of the given convex lens is equal to +4 D.