Hey Everyone!
I know its been a while, so thanks for your patience!
Right... we know what waves are, how they behave, etcetcetc. Now, we can start to understand what the heck happens when two waves interact. This post is going to cover very simple, one-dimensional wave interference, and the next post (in about an hour at most) will cover more complex two-dimensional wave interference
One-dimensional wave interference between two continuous waves of an equal amplitude, wavelength, and frequency produces a standing wave. A standing wave has NO net transfer of energy from one point to another. This means that a standing wave... well, stands.
When the crest of one wave meets the crest of the other (or a trough meets a trough), it results in constructive interference- the amplitude of the resultant wave is 2x greater than the amplitude of either of the two waves. When a crest meets a trough, however, it results in destructive interference- the amplitude of the resultant wave is less than either of the two waves. In the case of a standing wave, this simply means that the two
waves cancel out.
There are two very important points on a standing wave: Nodes and antinodes. An antinode is a point where there is ALWAYS constructive interference, while a node is a point where there is ALWAYS destructive interference. At a node, both waves always cancel each other out- the nodes never move!
The equation we need for standing waves are:
Where n is the number of nodes along the length of the medium, lambda is wavelength, and l is the length of the string/medium. Then, of course, there is the standard equation for waves:
wave speed = wavelength * frequency
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