Randall D. Knight — Traveling Waves: Problem 72

Some modern optical devices are made with glass whose index of refraction changes with distance from the front surface. FIGURE P16.72 shows the index of refraction as a function of the distance into a slab of glass of thickness \( L \). The index of refraction increases linearly from \( n_1 \) at the front surface to \( n_2 \) at the rear surface. a. Find an expression for the time light takes to travel through this piece of glass. b. Evaluate your expression for a 1.0-cm-thick piece of glass for which \( n_1 = 1.50 \) and \( n_2 = 1.60 \).