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Question: Answered & Verified by Expert
A double convex thin lens made of the refractive index 1.6 has radii of curvature 15 cm each. What is the focal length (in cm) of this lens when immersed in a fluid of refractive index 1.63?
PhysicsRay OpticsJEE Main
Solution:
2718 Upvotes Verified Answer
The correct answer is: -407.5
Focal length of lens in given by

1fw= μg-11R1-1R2

=1.61.63-1115+115

=-0.03×21.63×15=.061.63×15

so,  fw= -8152

=-407.5 cm

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