Question

Why is the unit of the power of a lens called dioptre (D) ? Why not watt only

Answer 1

Answer:

power of lens is defined as reciprocal of the focal length of the lens Express in matter. Si unit of power isdipotre denoted by D. since the focal length is positive so it is convince lens since the focal length is negative so it is a concave lens

Answer 2

i never thought about this.Good question.

i checked dimensions of normal power(used in mechanics) and power of lens.

power in mechanics=w/t

=F×V

dimensions=ML^2T^-3

power of lens=1/focal length

dimensions=L^-1

they are totally different.

we are just calling them power

any way good thinking ○ ○

♡