The speed of propagation of a sine wave or a sinusoidal component of a complex wave, equal to the product of its wavelength and frequency.
〔物理〕相速
Example sentencesExamples
The speed of each frequency component is called phase velocity, while the packet's speed is called group velocity.
Perhaps the reported observation, if confirmed, may reveal a hitherto unknown property of light: the apparently excessive speed might be something like phase velocity.
For example, the phase velocity of a wave packet is a pseudo process but the group velocity is a causal process; yet both licence reliable predictions.
Notice the light wave is still only propagating at c, the phase velocity of the wave, however, may travel less, or even greater than at the speed of light.
Even when the phase velocity is faster than light, the group velocity should be slower.