is an integral number of wavelengths farther from one source than the other. If the difference in path lengths is a half integer number of wavelengths, destructive interference occurs. The red dots show locations where constructive interference occurs. The white dots indicate where destructive interference occurs. Example Loudspeakers A and B are set up on the X axis some distance apart. Both speakers vibrate in phase at 68.6 hz and the speed of sound is 343 m/s. Point C is 1.0 meter from speaker A and the line connecting A with C makes a 60 degree angle with the X axis. Find the minimum distance between the speakers that will produce destructive interference at point C. Diffraction When a wave encounters an opening or an obstacle, the wave spreads out in all directions passing through the opening or by the edge of the obstacle. This bending is called diffraction. Bending occurs because each vibrating molecule in the opening acts as a new source for a wave. Using the principle of linear superposition, we can see that the waves from all of these molecules add together to produce a resultant wave that spreads out in all directions. Constructive and destructive interference occur at specific directions of travel depending on the size of the opening and the wavelength of the wave. The strongest constructive interference occurs directly in front of the opening. Other areas of constructive and destructive interference occur but become increasingly weaker as the direction moves away from directly in front of the opening.
is an integral number of wavelengths farther from one source than the other. If the difference in path lengths is a half integer number of wavelengths, destructive interference occurs. The red dots show locations where constructive interference occurs. The white dots indicate where destructive interference occurs. Example Loudspeakers A and B are set up on the X axis some distance apart. Both speakers vibrate in phase at 68.6 hz and the speed of sound is 343 m/s. Point C is 1.0 meter from speaker A and the line connecting A with C makes a 60 degree angle with the X axis. Find the minimum distance between the speakers that will produce destructive interference at point C. Diffraction When a wave encounters an opening or an obstacle, the wave spreads out in all directions passing through the opening or by the edge of the obstacle. This bending is called diffraction. Bending occurs because each vibrating molecule in the opening acts as a new source for a wave. Using the principle of linear superposition, we can see that the waves from all of these molecules add together to produce a resultant wave that spreads out in all directions. Constructive and destructive interference occur at specific directions of travel depending on the size of the opening and the wavelength of the wave. The strongest constructive interference occurs directly in front of the opening. Other areas of constructive and destructive interference occur but become increasingly weaker as the direction moves away from directly in front of the opening.