question_answer

A thin convex lens made from crown glass\[\left[ \mu =\frac{3}{2} \right]\] has focal length\[f\]. When it is measured in two different liquids having refractive indices \[\frac{4}{3}\] and \[\frac{5}{3},\] it has the focal lengths \[{{f}_{1}}\] and \[{{f}_{2}}\] respectively. The correct relation between the focal lengths is:                                                      [JEE MAIN 2014]

A) \[{{f}_{2}}>f\] and \[{{f}_{1}}\] becomes negative

B) \[{{f}_{1}}\]and \[{{f}_{2}}\] both become negative

C) \[{{f}_{1}}={{f}_{2}}<f\]

D) \[{{f}_{1}}>f\] and \[{{f}_{2}}\]becomes negative

Correct Answer: D

Solution :

[d]         ...(1)

...(2)

(3)

From (1)

From (2)

From (3)