Two similar thin equiconvex lenses, of focal length f each, are kept coaxially in contact with each other such that the focal length of the combination is 
. When the space between the two lens is filled with glycerine (which has the same refractive index ( 
) as that of glass), then the equivalent focal length is 
. The ratio 
will be
A
B
C
D
Text Solution
Verified by ExpertsThe correct answer is:
C
In case I:
Equivalent focal length
In case II:
or 
Equivalent focal length
or 
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