A compact disk uses the interference of reflected waves from the CD to encode information. Light from a red laser ( = 630 nm) is

A compact disk uses the interference of reflected waves from the CD to encode information. Light from a red laser (λ = 630 nm) is reflected from small pits in the CD, and waves from the bottom of a pit and the adjacent top edge interfere (Fig. P25.20). What is the minimum pit depth for which the two waves interfere destructively? Assume this pit is on the surface of the CD so that the region above the pit is air.