Question

How does the power of lens vary with its focal length?

Answer 1

Converging lenses have positive optical power, while diverging lenses have negative power. When a lens is immersed in a refractive medium, its optical power and focal length change.

Answer 2

Power of a lens decreases as the focal length of the length increases

Explanation:

Power of lens is defined as the efficiency with which a lens can converge or diverge the light ray.

The reciprocal of focal length of the lens is called the power of the lens (P).

Power of lens, $P = \frac{1}{f}$

The S.I unit of power of lens is dioptre denoted by D.

Thus, power of a lens decreases as the focal length of the length increases.