Search results
Results From The WOW.Com Content Network
Propagation of a wave packet demonstrating a phase velocity greater than the group velocity. This shows a wave with the group velocity and phase velocity going in different directions. The group velocity is positive, while the phase velocity is negative. [1] The phase velocity of a wave is the rate at which the wave propagates in any medium.
Conversely, a phase reversal or phase inversion implies a 180-degree phase shift. [ 2 ] When the phase difference φ ( t ) {\displaystyle \varphi (t)} is a quarter of turn (a right angle, +90° = π/2 or −90° = 270° = −π/2 = 3π/2 ), sinusoidal signals are sometimes said to be in quadrature , e.g., in-phase and quadrature components of a ...
The phase velocity varies with frequency. The phase velocity is the rate at which the phase of the wave propagates in space. The group velocity is the rate at which the wave envelope, i.e. the changes in amplitude, propagates. The wave envelope is the profile of the wave amplitudes; all transverse displacements are bound by the envelope profile.
The group velocity is positive (i.e., the envelope of the wave moves rightward), while the phase velocity is negative (i.e., the peaks and troughs move leftward). The group velocity of a wave is the velocity with which the overall envelope shape of the wave's amplitudes—known as the modulation or envelope of the wave—propagates through space.
Characteristic phases of a water wave are: the upward zero-crossing at θ = 0, the wave crest at θ = 1 / 2 π, the downward zero-crossing at θ = π and; the wave trough at θ = 3 / 2 π. A certain phase repeats itself after an integer m multiple of 2π: sin(θ) = sin(θ+m•2π).
Here ψ is the angle between the path of the wave source and the direction of wave propagation (the wave vector k), and the circles represent wavefronts. Consider one of the phase circles of Fig.12.3 for a particular k, corresponding to the time t in the past, Fig.12.2. Its radius is QS, and the phase chevron side is the tangent PS to it.
A Kelvin wave is a wave in the ocean, a large lake or the atmosphere that balances the Earth's Coriolis force against a topographic boundary such as a coastline, or a waveguide such as the equator. A feature of a Kelvin wave is that it is non-dispersive , i.e., the phase speed of the wave crests is equal to the group speed of the wave energy ...
As in time reversal, the wave re-emitted by a phase conjugation mirror will auto-compensate the phase distortion and auto-focus itself on its initial source, which can be a moving object. [1] Propagation of a time reversal replica demonstrates a remarkable property of phase-conjugated wave fields. [2]