Superposition and Interference

SUPERPOSITION AND INTERFERENCE

Most waves are not simple waves. Most waves are complex because they are added together and subtracted from one another. This can be seen when looking at the waves on the ocean, which will have different heights at different times. Waves will superimpose upon themselves onto one another. This is referred to as superposition. The disturbances in these cases will be referred to as forces that will either add or subtract from one another. If two waves come together with the same peaks and same troughs, this will be called constructive interference. The wave will have twice the amplitude of individual waves but the wavelength will be the same.

On the other hand, if two waves are identical and have the trough of one happen at the peak of another, this is referred to as destructive interference. Because the disturbances are in direct opposition to one another, the end result is a zero amplitude and no wavelength as the waves will cancel one another completely. In order for this to occur, the waves must be precisely identical and directly opposite to one another. This can happen to sound waves when stereo sound is used.

Most wave additions and subtractions are not so simple. A large wave with a long wavelength and a small wave with a short wavelength will add together and will create an odd, complicated wave that has some periodicity that can be described. This will be a combination of constructive and destructive interference.

Some waves will vibrate and will seem not to move directly. These types of waves can be seen in wave addition and subtraction of waves traveling in opposite directions. The resultant wave is described as a standing wave. Standing waves can be seen in organ pipes and with guitar strings; they look like quivering or vibration and will not appear to travel in any direction whatsoever. Nodes are the points where the string does not move and the wave disturbance is zero, while an antinode is the location of maximum wave amplitude. The frequency is related to the velocity of the wave.

The lowest frequency of this type of wave addition and subtraction is called the fundamental frequency. This type of thing can be seen in sound waves, in which the