constructive
2t = n / 2, 3 n / 2, 5 n / 2, . To know whether interference is constructive or destructive, you must also determine if there is a phase change upon reflection. Thin film interference thus depends on film thickness, the wavelength of light, and the refractive indices. For white light incident on a film that varies in thickness, you will observe rainbow colors of constructive interference for various wavelengths as the thickness varies. Example 27.7 Soap Bubbles: More Than One Thickness can be Constructive a What are the three smallest thicknesses of a soap bubble that produce constructive interference for red light with a wavelength of 650 nm? The index of refraction of soap is taken to be the same as that of water. b What three smallest thicknesses will give destructive interference? Strategy and Concept Use Figure 27.33 to visualize the bubble. Note that water . There is a.