What is actually phase velocity?

[rozan977]

What is actually phase velocity??

When a body moves aren't we supposed to say that each particles on the body moves with same velocity and so the de-broglie wave corresponding to each particle must have the same velocity. Then why should a wave representation of moving body correspond to a wave packet??

 

[Bob_for_short]

When a body moves aren't we supposed to say that each particles on the body moves with same velocity and so the de-broglie wave corresponding to each particle must have the same velocity. Then why should a wave representation of moving body correspond to a wave packet??

A body has the center of inertia coordinates R and the relative ones r_i. The center of inertia can be described with a plane de Broglie wave if the body is free, and the relative coordinates normally describe oscillations and rotations of particles around the center of inertia. The corresponding wave function describes a bound particle state.

 

[Bob S]

See
http://www.mathpages.com/HOME/kmath210/kmath210.htm

 

[I_am_learning]

When a body moves all of its constituent particle moves with same velocity
(provided that the body is in rectilinier motion). But what we are dealing in quantum mechanics is the motion of each such individual particle.
Even the motion of each such individual particle can't be accounted by a simple SHM wave equation. It needs to be defined by the superposition of several wave equation each varying slightly in wavelength and frequency. The result is that the position of maximum Amplitute constantly drifts away with a velocity known as group velocity. This velocity is also the velocity of the object.