Question

A monochromatic beam of light passes from an optically denser medium into an optically rarer medium. As a result, ____.

• A. its velocity increases
• B. its velocity decreases
• C. its frequency decreases
• D. its wavelength decreases

Answer 1

The correct option is A

its velocity increases

The speed of light in a medium depends on the optical density of the medium. For a medium with higher optical density, the speed of light in the medium is lesser. Therefore, when a light ray enters an optically rarer medium from an optically denser medium, its speed increases. It may be however noted that the frequency of the ray does not change with a change in the medium.