An equiconvex lens made of glass of refractive index 
has focal length 
in air. It is completely immersed in water of refractive index 
. The percentage change in the focal length is
A
increase
B
decrease C
decrease
D
increase
Text Solution
Verified by ExpertsThe correct answer is:
D
: Refractive index of lens, 
From lens maker's formula 
For equiconcave lens, 
Karnataka-CET Chapterwise Solutions Rhysics
or 
Now, when the lens is immersed in water of refractive index, 
, then
or 
or 
Percentage change in focal length
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