Question

pls solve its urgent
I will mark as brainlist​

Answer 1

Answer : Power : -0.025. Focal Length : 20 cm

Explanation :

Power of Lens = 1/focal length

Also, when two lens are in contact then the power of combination of the two is :-

P1 + P2 + P3 + ...

=> 1/f1 + 1/f2 + 1/f3 …

But, here we have only two lens. So,

1/20 +1/40

=> 0.05 + 0.025

But, there is also a theory that the power of convex lens is positive and that of a concave lens is negative.

Therefore, (-0.05) + 0.25

= -0.025

Now about the focal length. There is a theory that the focal length of convex lens is positive and that of concave lens is negative. Therefore, the focal length = 40 - 20 = 20 cm