11.S: Interference (Summary)
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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 |
Key Equations
Constructive interference | Δl=mλ, for m = 0, ±1, ±2, ±3… |
Destructive interference | Δl=(m+12)λ, for m = 0, ±1, ±2, ±3… |
Path length difference for waves from two slits to a common point on a screen | Δl=dsinθ |
Constructive interference | dsinθ=mλ, for m = 0, ±1, ±2, ±3… |
Destructive interference | dsinθ=(m+12)λ, for m = 0, ±1, ±2, ±3… |
Distance from central maximum to the m-th bright fringe | ym=mλDd |
Displacement measured by a Michelson interferometer | Δd=mλ02 |
Summary
3.1: Young's Double-Slit Interference
Samuel J. Ling (Truman State University), Jeff Sanny (Loyola Marymount University), and Bill Moebs with many contributing authors. This work is licensed by OpenStax University Physics under a Creative Commons Attribution License (by 4.0).