Superposition of two waves

In physics 7 we normally consider two infinite waves that come together. Mainly this is so we do not have to worry about how the wave is created. However, sometimes it is difficult to think about what it means for these waves to be travelling.

In the following movie, we consider two waves travelling on a string. One is travelling to the left, and the other is travelling to the right. Before the waves overlap it is wasy to see what they are going to do. To work out what happens as they overlap, we consider what would happen to each wave if the other wave was not there. To do this, we draw two graphs: the one on travelling to the right, and beneath that the left travelling wave.

It should be remembered that there is only one string, not two. The real string is shown in red and has two "bumps". Because it is easier to see what happens to the two bumps separately, we usually picture the wave on the top and the wave on the bottom independently. The amazing thing is that this works: adding these two waves together tells us what happens to the wave on the real string.

Click here to see the movie