You place one glass slide on top of another, with an animal hair between them at one end. You illuminate the slides with blue light of wavelength $450\mathrm{nm}.$ You count along the slide and find 300 transitions from bright to dark and back to light. How thick is the hair?

A thin film of soap (n = 1.34) coats a piece of flat glass (n = 1.52). What is the minimum film thickness if it reflects 643-nm red light most strongly when illuminated normally by white light?

Use your expression from part a to find an expression for the separation Δy on the screen of two fringes that differ in wavelength by Δλ.

FIGURE EX33.17 shows the interference pattern on a screen 1.0 m behind an 800 lines/mm diffraction grating. What is the wavelength (in nm) of the light?