Introduction: The refraction of light refers to the bending of light as is travels from one medium to another. Whenever light travels from one medium to another to cause refraction, there is a difference in what is known as the refractive index, or the ratio of the velocity of light in a vacuum to its velocity in a specified medium. The equation relating the indices of refraction and the angle of refraction is shown below, known as Snell's Law:

[math]n_1sintheta_1=n_2sintheta_2[/math], where n=index of refraction and [math]theta[/math]=angle from the normal of the boundary

Based on Snell's Law, light is refracted either to a lesser angle or to a greater angle. It is important to note that in media like water, compared to air, the angle of light to water would be smaller, hence leading to refraction towards the normal line. This is because light travels more slowly in water. On the other hand, in air, light travels more rapidly in comparison to water, so its angle to the normal line would be greater. In general, the greater that the index of refraction is, the smaller the angle of light is to the medium and the more light refracts towards the normal line.