Q.

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.              [2023]


Ans.

(34)

From 1st lens  1v+16=124

1v=124-16=-18  v=-8 cm

From 2nd lens  1v+118=19

1v=19-118=118  v=18

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