Key Terms

coherent waves

waves are in phase or have a definite phase relationship

fringes

bright and dark patterns of interference

incoherent

waves have random phase relationships

interferometer

instrument that uses interference of waves to make measurements

monochromatic

light composed of one wavelength only

Newton’s rings

circular interference pattern created by interference between the light reflected off two surfaces as a result of a slight gap between them

order

integer m used in the equations for constructive and destructive interference for a double slit

principal maximum

brightest interference fringes seen with multiple slits

secondary maximum

bright interference fringes of intensity lower than the principal maxima

thin-film interference

interference between light reflected from different surfaces of a thin film