Interference of circular surface waves

Two point sources emit circular waves that interfere with each other. Different interference patterns can be produced by adjusting the wavelength, the positions, the amplitudes, and the phases. Red is positive and blue is negative. Black regions have no wave amplitude.

• to see the circular waves emitted by the other source.
• The far field is defined as those locations that are much further away from both sources than the distance between the sources and much farther away from the sources than a wavelength. Locations closer to the sources are called the near field. Put the sources close together and choose a short wavelength. You should see that there are certain directions where the waves interfere destructively in the far field and other directions where the waves interfere constructively in the far field.
• Increase the phase of one of the sources in small steps to see the influence this has on the interference pattern.