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## Main Question or Discussion Point

Hello!

Could somebody please tell me how i can compute the expectation value of the momentum in the case of a free particle(monochromatic wave)? When i take the integral, i get infinity, but i have seen somewhere that we know how much the particle's velocity is, so i thought that we can get it from the expectation value of its momentum.

Also, Wikipedia states(here: https://en.wikipedia.org/wiki/Free_particle#Measurement_and_calculations -- just scroll down a bit) that one CAN do the calculation via the integral and get hbar*k.

Thanks!

Could somebody please tell me how i can compute the expectation value of the momentum in the case of a free particle(monochromatic wave)? When i take the integral, i get infinity, but i have seen somewhere that we know how much the particle's velocity is, so i thought that we can get it from the expectation value of its momentum.

Also, Wikipedia states(here: https://en.wikipedia.org/wiki/Free_particle#Measurement_and_calculations -- just scroll down a bit) that one CAN do the calculation via the integral and get hbar*k.

Thanks!