Question

4. (l) State and define the SI unit of power of a lens.
(ii) A convex lens of focal length 25 cm and a concav
lens of focal length 10 cm are placed in close contac
with each other. Calculate the lens power of this
combination.​

Answer 1

Answer:

1.Power of lens is the ability of the lens to converge the rays of light falling on it. It can also be defined as P=1/f where f is the focal length. S.I. unit of power is D(Dioptre). It is represented by letter 'P'.

2.(l) State and define the SI unit of power of a lens. (ii) A convex lens of focal length 25 cm and a concav lens of focal length 10 cm are placed in close contac with each other. Calculate the lens power of this combination.​.

Explanation: