The physics of waves describes their behavior and wave phenomena such as reflection, refraction, dispersion, and interference. Interference is the phenomenon observed when two traveling wave trains coexist in the same medium. Consider single frequency waves described by a sine function and the following quantities: a period T, or the time required to complete a full cycle, a frequency ƒ, which is the reciprocal of the period, an amplitude A, which is the maximum displacement from the equilibrium position and a wavelength &lgr; which is the distance between two wave crests, or positions of maximum amplitude. If the sine crests of two waves traveling in opposite directions through the same medium completely overlap (i.e., become in-phase) their amplitudes add and the interference is referred to as constructive interference. A single wave with double amplitude is observed in the medium. If the two wave crests become...