1. A glass camera lens with an index of refraction of 1.55 is to be coated with a cryolite film (n = 1.3) to decrease the reflections of normally incident green light of wavelength 500 nm. How thick should such a film be?

2. Suppose you wanted to use a non-reflecting layer for radar waves to make an aircraft invisible. What would the thickness of the layer be to avoid reflecting 2 cm radar waves. (You can neglect changes of wavelength in the layer for this problem.) Would there be any problems as the aircraft turn? Can you imagine any other ways to use the wave nature of radar to try to make "stealth" aircraft? How could an on-board transmitter help?

3. A Michelson interferometer is illuminated with 500 nm light. One of the mirrors is moved so that 1000 fringes move past the crosshairs of the observing telescope. How much has the mirror moved? (Note the useful YouTube video)
How could you use an interferometer to tell if the wall of, say, a liquid storage tank buckles by a small amount when the tank is filled?

4. Two sources of electromagnetic radiation are in phase, and emit waves that have a wavelength of 0.44 m. Determine (and give an explanation) whether constructive or destructive interference occurs at a point whose distances from the sources are:

(A) 1.32 and 3.08 m

(B) 2.67 and 3.33 m

(C) 2.20 and 3.74 m

(D) 1.10 and 4.18 m