Define the power of lens. What is the meaning of "the power of lens is 1 dioptre" if the power of a lens -2.0D, then what type of lens is that? when an object is kept at infinity from this type of lens, what is the size of the image formed.

Explanation

The ability of a lens to converge or diverge the ray of light after refraction is called power (p) of the lens. It is defined as the reciprocal of the focal length i.e, `P= (1)/(f)` unit of power of a lens is diopter. A lens of focal length 100cm has a power of 1 dioptre i,e I dioptre = `1m^(-1)` If the power of a lens is 2 D then the type of lens is concave lens. The size of the image in this lens is highly diminished point sized.