A simple microscope consists of a concave lens of power of `- 10 D` and a convex lens of power `+ 30 D` in contact. If the image formed is at infinity, what is the magnifying power of microscope ? Take distance of distinct vision `= 25 cm`.

Answer

`5`

Explanation

Here, `P = P_(1) + P_(2) = - 10 + 30 = 20 D`
`F = (100)/(P) = (100)/(20) = 5 cm`
As final image is at infinity, therefore,
`M = (D)/(F) = (25)/(5) = 5`