A measure of how much the speed of light is reduced inside a medium compared to its speed in a vacuum

अपवर्तनांक, यह बताता है कि किसी माध्यम में प्रकाश की गति कितनी कम हो जाती है

English Usage: The index of refraction of water is approximately 1.33.

Hindi Usage: पानी का अपवर्तनांक लगभग 1.33 है।