Definition of group velocity in English:
The speed at which the energy of a wave travels.
- Essentially, the group velocity of the wave must fall to zero at that location, dropping in such a way that there is sufficient time for the damping to dissipate all of the wave's energy before it gets to that point.
- Even when the phase velocity is faster than light, the group velocity should be slower.
- He counters that when a beam passes between positive- and negative-index media the group velocity is negatively refracted.
Definition of group velocity in:
- British & World English dictionary