Question

A point object, 'O' is placed in front of two thin symmetrical coaxial convex lenses L₁ and L₂ with focal length 24 cm and 9 cm respectively. The distance between two lenses is 10 cm and the object is placed 6 cm away from lens L₁ as shown in the figure. The distance between the object and the image formed by the system of two lenses is _____ cm.

Answer 1

Correct Answer: 34

From 1st lens
1/v + 1/6 = 1/24
1/v = 1/24 - 1/6 = -1/8
v = -8 cm

From 2nd lens
1/v + 1/18 = 1/9
1/v = 1/9 - 1/18 = 1/18
v = 18 cm

So distance between object and its image:
6 + 10 + 18 = 34 cm