The Maxwell Relation approximates it as the square root of the dielectric constant, and the ratio of this quantity for two materials is equal to the ratio of the (*) sines of the incident angles by Snell's Law.
A complex variety of this quantity includes an imaginary term proportional to the electrical conductivity over the angular frequency. Cauchy's Formula gives this quantity as a function of one over the wavelength squared. The Maxwell Relation approximates it as the square root of the dielectric constant, and the ratio of this quantity for two materials is equal to the ratio of the (*) sines of the incident angles by Snell's Law. For 10 points, name this quantity that gives the ratio of the speed of light in a vacuum to the speed of light in a material.
A complex variety of this quantity includes an imaginary term proportional to the electrical conductivity over the angular frequency.
{index} of {refraction} [or {refractive index;} prompt on {n}]