Question

why refractive index doesn't have any SI units​

Answer 1

Answer:

Because the refractive index is expressed as a ratio of the speed of light in vacuum relative to that in the considered medium . As it is a ratio it is unitless . The units m/s or km/h cancel out each other. "Refractive index" is a dimensionless unit.

Explanation:

HOPE YOU UNDERSTAND

Answer 2

Answer:

Explanation:refractive index is ratio between two medium (either between speed of light or angle of refraction and angle of incidence.