Question

When is the superposition of periodic waves periodic?

Answer 1

You mean when is the resultant wave periodic?

Answer 2

Yeah

Answer 3

http://fooplot.com/#W3sidHlwZSI6MCwiZXEiOiJzaW4oeCkrc2luKDN4KSIsImNvbG9yIjoiIzAwMDAwMCJ9LHsidHlwZSI6MTAwMH1d

Almost always

Answer 4

http://fooplot.com/#W3sidHlwZSI6MCwiZXEiOiJzaW4oeCkrc2luKC14KSIsImNvbG9yIjoiIzAwMDAwMCJ9LHsidHlwZSI6MTAwMH1d
Except in special cases

Answer 5

http://fooplot.com/#W3sidHlwZSI6MCwiZXEiOiJzaW4oeCkrc2luKDN4KS8zK3Npbig1eCkvNStzaW4oN3gpLzcrc2luKDl4KS85K3NpbigxMXgpLzExIiwiY29sb3IiOiIjMDAwMDAwIn0seyJ0eXBlIjoxMDAwfV0- some quite interesting

Answer 6

Yeah, constructive and destructive interference, depending on their phase relationship. Completely out of phase, total destruction into nothing, completely in, their amplitudes are added. If in/out of phase not completely, then they still interfere but its get more complicated, they still add/subtract each others amplitude but instantaneously at each point, similar to the image henpen put up

Answer 7

Yeah got it thanx guys