group speed
group velocity
noun
physics
the speed at which energy is propagated in a wave. This is the quantity determined when one measures the distance which the radiation travels in a given time. In a medium in which the speed increases with wavelength the group speed is less than the phase speed, and vice versa
Words nearby group speed
Example sentences from the Web for group speed
In a vacuum there is no dying out of the waves, so that the group-speed and the wave-speed are identical.