Multiple choice

Which of the following is the unit of refractive index?

  1. Degree

  2. Kelvin

  3. It has no unit

  4. None of these

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Refractive index is a ratio of two speeds (speed of light in vacuum to speed of light in the medium), so the units cancel out, making it a dimensionless quantity.