Snell's law of refraction

A ray of light traveling through medium $\text A$start text, A, end text is incident on another medium $\text B$start text, B, end text, where it refracts making an angle of $60\degree$60, degree with the normal.

The refractive index of medium $\text B$start text, B, end text with respect to medium $\text A$start text, A, end text, $n_{\text{BA}}=\sqrt{\dfrac{2}{3}}$n, start subscript, start text, B, A, end text, end subscript, equals, square root of, start fraction, 2, divided by, 3, end fraction, end square root.