The refractive index of a liquid is 1.5. If the velocity of light in vacuum is 3.0 x 10^8 ms‾¹; the velocity of light in the liquid is

A. 1.5 x 10⁸ms⁻¹
B. 2.0 x 10⁸ms⁻¹
C. 3.0 x 10⁸ms⁻¹
D. 4.5 x 10⁸ms⁻¹

Correct Answer:

Option B = 2.0 x 10⁸ms⁻¹

Explanation

n = ^{speed in air}/^{speed in glass}

1.5 = ^{3×10^4}/_{speed in glass}
Speed in glass = ^{3 x 10^8m/s} / _1.5

= 2 x 10⁸m/s