6A40.36 - Interference - Air and Water (Db. Slit)

Code Number:
Demo Title:
Interference - Air and Water (Db. Slit)
Diffraction of Waves
Area of Study:
Optics, Astronomy
Laser with diffusing lens, Cornell plate (db. slit)., refraction trough, lab jacks, screen.

Set up the equipment as shown with the double slit and beam at the lens end of the refraction trough.  Several adjustments have to be made with the tank and the laser so that the two patterns fall one on top of the other.  Due to the index of refraction of the water this probably means that the laser and the tank will not be exactly level.  When properly adjusted a 3 bar pattern in the air should have a 4 bar pattern under it through the water.

  • Brian Houser, "Demonstrating the Decreased Wavelength of Light in Water", TPT, Vol. 39, #4, Apr. 2001, p. 228.
  • P.J. Ouseph, "Refraction of Diffracted Light", TPT, Vol. 36, #7, Oct. 1998, p. 420. 
  • G.R. Davies, "Interference and Diffraction Corridor Demonstrations", TPT, Vol. 33, #4, Apr. 1995, p. 244.
  • Simon George and Robert Doebler, "Index of Refraction Using a Diffraction Pattern in a Fishtank", TPT, Vol. 29, #7, Oct. 1991, p. 462.
  • Douglas C. Jenkins and Frank A. Smith, Jr., "Lecture Hall Demonstrations Or Fundamental Optics Made Obvious", TPT, Vol. 18, #1, Jan 1980, p. Back Cover.
  • A. T. Mogill, "Velocity, Wavelength and Frequency Relations for Light", TPT, Vol. 13, #9, Dec 1975, p. 555.
  • Richard F. Kotheimer, "Fish Tank, Laser Diffraction", TPT, Vol. 12, #5, May 1974, p. 307.
  • T. Kallard, "Diffraction Refractometer", Exploring Laser Light, p. 203.
  • Shyam Singh, "Diffraction Method Measures Refractive Indices of Liquids", Physics Education, Vol. 39, #3, 2004, p. 273.

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