Interference with two sources

• The instantaneous intensity is drawn on a plane through the sources and on the screen (on the right). If average is positive, the third image displays the intensity averaged over average frames.
• Unit length is equal to the distance between sources and screen.
• On the left one can choose the amplitudes A1 and A2 of both sources, their wavelengths λ1 and λ2, the phase difference Δφ between them, and the phase velocity v.
• One can also change the distance between sources a and whether the latter are shown (fixed or oscillating).
• To get information on an element, put over it the mouse pointer to see the corresponding tooltip.

Activities

• Discuss what happens when the distance a between source changes. Try a = 0.3, 0.2 and 0.1, for instance.
• What happens if Δφ = 180?
• What happens if the amplitudes are different?
• And when the sources are incoherent?
  • Set a positive value for random, so that every so many steps the phase changes at random.
  • By setting average (somewhat) larger than random, you can see (very slowly) what one can expect from to incoherent sources. Sources may also be incoherent because they have different wavelengths (i.e., different frequencies, since we assume a single phase velocity).