Question
A thin convex lens made from crown glass 
has focal length f. When it is measured in two different liquids having refractive indices 4/3 and 5/3, it has the focal lengths f1 and f2 respectively. The correct
-
f1 = f2 <f
-
f1 >f and f2 becomes negative
-
f2 >f and f1 becomes negative
-
f1 and f2 both become negative
Solution
B.
f1 >f and f2 becomes negative
according to lens maker's formula, when the lens in the air.
In case of liquid, where refractive index is 4/3 and 5/3
we get
Focal length in first liquid
⇒ f1 is positive.
Focal length in second liquid
