Question

Two identical glass `(mu_(g)=3//2)` equi- convex lenses of focal length f each are kept in contact. The space between the two lenses is also filled with water `(mu_(g)=4//3).` The focal length of the combination is
A. f/3
B. f
C. `(4f)/(3)`
D. `(3f)/(4)`

Answer 1

Correct Answer - D
Using combination of lenses, we get
The focal length of the combination `rArr f_("eq")=(3f)/(4)`