Group and phase velocity of a wave

1. Dec 7, 2015

Sharlom

If i am given the de broglie wavelength
Of any particle then its sure that i can find the velocity of tat particle if its mass is given.
λ= h/mv
But the velocity which i found is the group velocity or phase velocity?

If it's not the group velocity
How can i find it?

2. Dec 7, 2015

Ken G

If the particle has a definite momentum, it has a definite velocity, so the group velocity is the same as the phase velocity in that case. They are different if you have a "wave packet", which is a state of indeterminate momentum.

3. Dec 7, 2015

Sharlom

If the particle electron is moving nearly at speed of light then also
Is phase and grp velocities the same?