A lens made of glass whose index of refraction is 1.60 has a focal length of + 20 cm in air. Its focal length in water, whose refractive index is 1.33, will be
A. three times longer than in air
B. two times longer than in air
C. same as in air
D. None of these
Answer:A
A lens made of glass whose index of refraction is 1.60 has a focal length of + 20 cm in air. Its focal length in water, whose refractive index is 1.33, will be
A. three times longer than in air B. two times longer than in air C. same as in air D. None of these