In refraction of light, sin i/sin r = constant in sin a particular case. What is this constant called?

Question

In refraction of light, \(\frac{sin\,i}{sin\,r}\) = constant in sin a particular case. What is this constant called?

Answer 1

The constant \(\frac{sin\,i}{sin\,r}\) (in a particular case) is called the refractive index of the second medium with respect to the first medium.