question_answer

Two thin symmetrical lenses of different nature and of different material have equal radii of curvature R = 15 cm. The lenses are put close together and immersed in water \[(a=4/3).\] The focal length of the system in water is 30 cm. The difference between refractive indices of the two lenses is

A) 1/2 

B) 1/4  

C) 1/3

D) 3/4