Physics – 3.2.2 Refraction of light | e-Consult

Relationship between Refractive Index and Critical Angle: The critical angle (θc) is directly related to the refractive indices of the two media involved. The greater the difference in refractive indices between the two media, the larger the critical angle will be. A larger difference means a greater amount of light will be reflected at the interface.

Calculation of Critical Angle: The critical angle (θc) can be calculated using Snell's Law, where the angle of refraction is 90 degrees. Snell's Law states: n1 * sin(θ1) = n2 * sin(θ2). When θ2 = 90 degrees, sin(θ2) = 1. Therefore, θc = arcsin(n2/n1). Where n1 is the refractive index of the denser medium and n2 is the refractive index of the rarer medium.

Example of Beneficial High Refractive Index: Diamond has a very high refractive index (approximately 2.42). This high refractive index is beneficial for making diamonds sparkle. When light enters a diamond, it undergoes internal reflection multiple times due to the large refractive index difference between diamond and air. This repeated internal reflection causes the light to be bent and dispersed, creating the characteristic brilliance and fire of a diamond. The higher the refractive index, the more pronounced this effect will be.