# Optics: Determine which of the following describe traveling waves

I'm really rusty on waves. What characteristics am I looking for? With respect to its variables, doesn't a valid wave equation have to contain only linear terms in its argument(s)?

http://i111.photobucket.com/albums/n149/camarolt4z28/IMG_20111009_211512.jpg?t= [Broken]

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ehild
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I'm really rusty on waves. What characteristics am I looking for? With respect to its variables, doesn't a valid wave equation have to contain only linear terms in its argument(s)?

Yes, a wave has the form f(ax-bt).

ehild

Yes, a wave has the form f(ax-bt).

ehild

Yes, I know that.

It appears (d) is valid, but what about (a), (b), and (c)? I guess I'm not sure what the squares do. Of course, I recognize the form of the equation without the squares.

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SammyS
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Having (ax±bt)2 shouldn't matter. The squaring can be considered to be part of function, f .

Having (ax±bt)2 shouldn't matter. The squaring can be considered to be part of function, f .

Same goes for cos2, too?

SammyS
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Same goes for cos2, too?
Yes.

What about (b)? It has az2 - bt2.

ehild
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If it is a travelling wave, in what direction does it travel? +z or -z?

ehild