Find the position of final image from first lens. Given focal length of each lens is 10 cm .

Step-by-step solution

(i) For refraction from lst lens, 1 f = 1 ~V - 1 u aligned & 1 ~V = 1 f + l u = 1 10 - 1 40 = 3 40 ~cm & v = 40 3 ~cm aligned This image acts as object for 2nd lens. Object distance for 2 nd lens L ₂=30- 40 3 = 50 3 ~cm (ii) Now for refraction from L₂, 1 v - 1 u = 1 f aligned & 1 v = 1 u + 1 f = 1 10 - 3 50 = 2 50 & v =25 ~cm aligned This image is object for 3rd lens, ( v =30-25=5 ~cm ) For L ₃, 1 v = 1 f + 1 u = 1 10 - 1 5 or v =-10 ~cm (location of final image =10 ~cm to left of L ₃ ) Distance from L ₁=30+(30-10)