the periodic disturbance in a medium resulting from the combination of two waves of equal frequency and intensity travelling in opposite directions. There are generally two kinds of displacement, and the maximum value of the amplitude of one of these occurs at the same points as the minimum value of the amplitude of the other. Thus in the case of electromagnetic radiation the amplitude of the oscillations of the electric field has its greatest value at the points at which the magnetic oscillation is zero, and vice versa

an oscillatory motion with a definite wavelength, frequency, and amplitude and having stationary, regularly spaced points where there is no motion: all the movement of the wave is contained between these nodes, thus providing for no net transport of energy