Young and Fresnel without sodium lamp
2015; Volume: 48; Issue: 3 Linguagem: Inglês
10.7149/opa.48.3.245
ISSN2171-8814
Autores Tópico(s)Experimental and Theoretical Physics Studies
ResumoespanolEl clasico experimento de las franjas interferenciales de Young empleando un biprisma de Fresnel para obtener la doble rendija suele realizarse con fuentes casi monocromaticas: una lampara espectral de sodio, un laser, etc. Incluso la explicacion teorica suele asumir que la fuente es monocromatica. Esto impide observar algunos aspectos del experimento, como que la interfranja aumenta con la longitud de onda. Ademas, origina un efecto negativo mucho mas grave, ya que induce a algunos estudiantes a concluir de forma erronea que las interferencias solo se producen cuando se emplean fuentes monocromaticas. En este articulo se muestra una sencilla modificacion del experimento empleando luz blanca y filtros RGB, la cual permite observar claramente interferencias con luz policromatica y verificar que la interfranja aumenta con la longitud de onda. EnglishThe well-known experiment of Young about interferences by means of a Fresnel biprism to obtain the double-slit is usually made using quasi-monochromatic sources: a sodium spectral lamp, a laser, etc. Besides, a monochromatic source is also assumed in order to develop the theoretical explanation of the experiment. Then, some experimental details are lost, as the dependence of the fringe-to-fringe spacing on the wavelength. Moreover, a much more dangerous negative effect is originated, since some students come to the following false conclusion: interference phenomena only are originated by monochromatic sources. In this paper, an easy modification of this experiment is shown. Thus, by employing a white source and RGB filters, it is possible to observe interference fringes with polychromatic light and verify that its period raises with the wavelength.
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