Double Slit Interference


This simulation shows the intensity resulting from Young's double slit experiment. The effects of interference and diffraction are calculated. Use the sliders to change the parameters of the experiment. Notice how the resulting intensity on the screen changes. You can use the check boxes to select whether interference, diffraction, or both together are shown.
  1. What parameter is the interference pattern independent of? How about the diffraction pattern?
  2. Turning diffraction off is equivalent to setting which parameter to zero?
  3. When the slit separation (d) is four times larger than the slit width (a), which interference maximum is missing?
  4. What other values of slit separation and area will result in missing maxima? Can you find a pattern?