The size of the image of an object, which is at infinity, as formed by a convex lens of focal length 30 ~cm is 2 ~cm . If a concave lens of focal length 20 ~cm is placed between the convex lens and the image at a distance of 26 ~cm from the lens, the new size of the image is

Step-by-step solution

Given, f₁=30 ~cm , aligned &f₂=-20 ~cm , h₀=2 ~cm &u₂=(30-26)=4 ~cm aligned Using lens formula for concave lens, 1 v₂ = 1 f₂ + 1 u₂ =- 1 20 + 1 4 = 4 20 = 1 5 or v₂=5 ~cm Magnification, m= v₂ u₂ = 5 4 =1.25 Also, m= h_ i h_ o =1.25 Size of new image, h_ i =h₀ 1.25=2 1.25=2.5 ~cm