Optics Question 591

Question: A thin convex lens of refractive index 1.5 has a focal length of 15 cm in air. When the lens is placed in liquid of refractive index 4/3 , its focal length will be

[CPMT 1974, 77; MP PMT 1992]

Options:

A) 15 cm

B) 10 cm

C) 30 cm

D) 60 cm

Show Answer

Answer:

Correct Answer: D

Solution:

flfa=(aμg1)(lμg1)

fl15=(1.51)(1.54/31)

fl=60cm



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