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I'm baffled by a problem in a quantum physics course I'm taking.

Problem: "Use the momentum operator to find an expression for the sum of two planewaves moving in opposite directions. Both planewaves have the same kinetic energy."

It's in one dimension only.

I know the momentum operator is (h_bar/i)(d/dx), and one planewave is exp(kx-wt). The other is exp(kx+wt) ??

My main problem is that I don't know quite where to start. :rofl: How should I use the momentum operator? The answer should be on the same form as a solution to the Scrodinger equation.. :uhh:

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# Homework Help: Sum of two planewaves using momentum operator

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