consider an alternating current of sinusoidal waveform having a maximum or peak value of4 ampers. the current square curve can be plotted to represent the instantaneous values of the heating effect; the mean height of this curve can be determined and will be found to be half of the maximum height, ie half of 16 = 8. this is shown on the diagram ( Fig 126 ). the number of amperes of continuous current that would give the same heating effect will be =2828 amperes and thus is the square-root of the mean of the squares of the current, ie true r.m.s. value