Question

define power of lens and write its unit? one student is uses a lens of focal length 50 cm and another of -50 cm, what is the nature of lens and its power?

Answer 1

power of lens is defined as the abality to converge or diverge the light ray.

it is the reciprocal of focal length.

its si unit is dioptre(D)

50 cm convex lens (converging lens)

-50 cm concave lens (diverging lens)

power +2d (convex lens)

-2d (concave lens)