Question

what does meant by power of lens? what does its sign (+ve or_ve ) indicate

Answer 1

*Power of the lens is reciprocal of the focal length of a lens
*The positive sign of the power denotes the convex lens
*The negative sign of the power denotes the concave lens
For example for a myopic eye the power of lens is - so this the depicts that we must use the concave lens and vice versa for hypermetropia

Answer 2

Power of lens is the ability of the lens to converge the rays of light falling on it.


Definition :

The power of a lens is the reciprocal of its focal length in meters.

1 P (power)
= 1 / f ( in meters) Dioptre.

___________

Sign (+ve or -ve ) indicates

The positivity or negatively of the

Focal length,
Object distance, or
Image distance, etc.




Hope it will help you.