Question

How does the power of a lens change if its focal length decreases to half? What is the unit of power of lens?

Answer 1

✫Answer✫

By formula, we know that :-

Power = 1/ (Focal Length)

So, if focal length decreases by half, power will become double.

Unit of power of lens is Diopter .

Answer 2

 If its focal length decreases to half, the power of the lens will get doubled.

• The focal length and power of the lens are related by the formula:

          $Power of lens=\frac{1}{focal length}$

• Therefore, if the focal length is decreased to half, the power of the lens will get doubled.

The SI unit of power of the lens is Dioptre.

• It is the inverse of focal length.
• $1 D = \frac{1}{m}$  

       (where m stands for meter)

• The term dipotre was proposed by Ferdinand Monoyer in 1872