WAVE MOTION

A wave is a method of energy transfer between two points. We can observe waves in ropes, slinky coils and ripples on water and sound in air. The diagram opposite shows the pattern we might expect in a rope that it is "carrying" a wave. Note that the particle at any horizontal displacement on the wave, is oscillating about the midpoint with what appears to be simple harmonic motion, this is the particle motion. The displacement of any particle on the wave motion, a distance x along a wave with wavelength l and frequency f is given by y = a sin( 2 π [ f t - x / l ] ) The x / l in the above equation represents the phase difference between the point at x = 0 and x, note than when x = l, the phase difference is 2 π radians or effectively zero, so they are inphase again and at the same stage in their motion.