Question

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 the above

Answer 1

Explanation:

option a is correct 3 time longer than in air