User:2004Åñï/sandbox

The refraction of light is defined as the change in the direction of the path of light when it passes from one transparent medium to the other transparent medium with varying refractive indeces, which is generally a surface phenomenon and follows the Snell's law of refraction. According to Snell's law of refraction, the ratio of the sine of the angle of incidence in the first medium to the sine of the angle of refraction in the second medium is constant for a give pair of media and a given colour of light and is mathematically equal to the refractive index costant (sin i / sin r = 1u2).Like reflection, the incident ray, the refracted ray and the normal at the point of incidence all lie in the same plane.

Critical angle(ic) for a given pair of media is defined as the angle of incidence in the denser medium corresponding to which the angle of refraction in the rarer medium is 90o.When a ray of light travelling in a denser medium is incident at the surface of a rarer medium at an angle of incidence greater than the critical angle(ic) for the pair of media, the ray is totally reflected back into the denser medium without any loss of energy or intensity. Hence for total internal reflection to take place, the light must travel from a denser to a rarer medium and the angle of incidence must be greater than the critical angle for the pair of media.