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Worksheet: Interferometry


In a Michelson interferometer, light of wavelength 632.8 nm from a He-Ne laser is used. When one of the mirrors is moved by a distance , 8 fringes move past the field of view. What is the value of the distance ?

  • A
  • B
  • C
  • D
  • E


An experimenter detects 251 fringes when the movable mirror in a Michelson interferometer is displaced. The light source used is a sodium lamp, wavelength 589 nm. By what distance did the movable mirror move?


What is the distance moved by the traveling mirror of a Michelson interferometer that corresponds to fringes passing by a point of the observation screen? Assume that the interferometer is illuminated with a 606 nm spectral line of krypton-86.

  • A m
  • B m
  • C m
  • D m
  • E m


In a thermally stabilized lab, a Michelson interferometer is used to monitor the temperature to ensure it stays constant. The movable mirror is mounted on the end of a 1.00-m-long aluminum rod, held fixed at the other end. The light source is a He Ne laser, . The resolution of this apparatus corresponds to the temperature difference when a change of just one fringe is observed. Find the temperature difference. Use a value of for the thermal expansion coefficient of aluminum.


A 5.08-cm-long rectangular glass chamber is inserted into one arm of a Michelson interferometer using a 633-nm light source. This chamber is initially filled with air at standard atmospheric pressure but the air is gradually pumped out using a vacuum pump until a near perfect vacuum is achieved. How many fringes are observed moving by during the transition?


A microscope slide is 10.0 cm long. One end of the slide is separated from a glass plate by a sheet of paper, while the other end of the slide is in contact with the glass plate. The slide is illuminated from directly above by light from a sodium lamp that has a wavelength . A fringe pattern is seen along the slide, the pattern contains 14 fringes per centimeter. The slide is then immersed in an unknown liquid. When immersed in the liquid, 18 fringes per centimeter are observed. What is the liquid’s refractive index?