Question

Light travels with a speed in water than in air.

• A. faster
• B. slower
• C. equal

Answer 1

The correct option is B slower

The speed of light depends on the optical density of a medium. Refractive index is the measure of the optical density of a medium. The speed of light is inversely proportional to the optical denstity (refractive index) of a medium. Water is optically denser than air, i.e. it has a higher refractive index than air. Hence, light travels slower in water than in air.