Educator

Refraction of Light, Part 2

• The index of refraction depends on the light wavelength; this explains phenomena such as the color spectrum emerging when white light strikes a prism, or the formation of the rainbow after a winter storm.
• When light travels in a region 1 and strikes the surface, separating it from region 2, at an angle theta, then if n_1 > n_2, there exists a critical value for theta beyond which total internal reflection occurs. The value of the critical angle is given by the relation sin(theta_critical) = n_2 / n_1.
• A convex lens (biconvex or plano-convex) is a converging lens; if parallel rays of light strike the lens on one side, they converge to a point on the other side. A concave lens, on the other, hand is a diverging lens.