Question

A double convex thin lens made of glass of refractive index 1.6 has radii of curvature 15 cm
each. The focal length of this lens when immersed in a liquid of refractive index 1.63 is
a) -407 cm b) 250 cm
c) 125 cm
d) 25 cm. Explain
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Answer 1

Answer: The answer would be -407cm