now super position might sound all fancy but it's really something that you'll have seen many times before if you have a source of w waves and another source we tend to find that the two uh sets of waves move through each other and when they meet at a point the displacement or the total displacement is equal to the sum of their individual displacements we can look at this superposition of waves graphically in a number of ways imag imag we had a fairly large wave with a large amplitude and a long wavelength if we think about a wave like that and we have that maybe playing perhaps a sound wave if we played another sound wave at the same time perhaps this one had a smaller amplitude and a higher frequency what we could look at is the sum of these two waves and we can do that by adding their individual displacements at any time and looking at what that looks like and what we get is something a bit like this now it's not easy to draw but effectively what we have is uh the the smaller wave superimposed onto the top of the wave and this is uh you know perhaps the the way that frequency modulation works and how a carrier wave uh allows us to transmit data and especially radio programs over a long distance we can also look at this in a couple more um of examples so perhaps I had a small wave that went up and down and we could look at things like its frequency and its amplitude and so on now perhaps we had a very similar wave that had the same uh frequency and therefore the same phase difference of its waves maybe a similar amplitude and what we could do is we could look at how these two waves interact and what we can do is maybe add this wave to this wave and what we get then is resultant uh and by applying or adding up their individual displacements at any time what we' get is a wave that has twice the amplitude as what we started with and this is what we call constructive interference this is because as a two ways interfere with each other they construct a bigger wave than what they started with so this is a bit like a load of individual voices perhaps in a crowd and they all get added together and they make the whole crowd sound louder than that one voice we can also look at the example where we have a similar wave to begin with and this time the second wave is 180° out of phase so that means whenever the this is at its maximum positive amplitude this is at its maximum negative displacement down here and again if we look at summing up these two waves together what we get is something that looks like this the two waves have canceled each other out and this is what we call destructive interference