PHY222 Midterm Study Guidance: Waves, Interference, Thermodynamics

Monochromatic light of wavelength 500 nm falls on two narrow slits that are 0.04 mm apart, generating an interference pattern on a distant screen. At what angle (in degrees) does the first minima occur in the interference pattern?

A light beam traveling through air ($n=1.00$) reflects perpendicularly off the top and bottom surfaces of a thin layer of oil ($n=1.50$) floating on water ($n=1.33$). What is the thinnest layer of oil that will give rise to constructive interference at a wavelength of 700 nm?

A soap film ($n=1.35$) of thickness 150 nm is surrounded by air ($n=1.00$) on both sides. If light of a certain wavelength is beamed at the soap film perpendicular to its surface, what is the longest wavelength of light for which you’ll see no reflection?