Question

plzz give steps to solve the numerical given​

Answer 1

Answer:

here is ur answer!! The deviation of the incident light rays produced by a lens on refraction through it, is a measure of its power. when focal length is 40 that mean it is positive so therefore the resulting power will also be positive. If the power is positive it considered as power of convex lens.

Answer 2

Explanation:

Power of a lens is the ability to converge or diverge the ray of light falling on it. Power of a lens is defined as reciprocal of focal length of the lens.

SI Unit - dioptre

formula-

p=1/f(in metres) & 100/f(in cm)

f=40cm

power=?

p= 100/f(in cm)

p=100/40

p=2.5 D

the nature of lens is Convex lens.

f = -20 cm

power = ?

p = 100/f(in cm)

p =100/-20

p = -5D

the nature of lens is Concave lens.

hope it helps

If u don't understand then let me know , I will solve it on paper and then send you