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The wave equation is a second-order linear partial differential equation for the description of waves or standing wave fields such as ... (where the wave speed is c 2 ...
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.
Wave speed is a wave property, which may refer to absolute value of: . phase velocity, the velocity at which a wave phase propagates at a certain frequency; group velocity, the propagation velocity for the envelope of wave groups and often of wave energy, different from the phase velocity for dispersive waves
with T the wave period (the reciprocal of the frequency f, T=1/f). So in deep water the phase speed increases with the wavelength, and with the period. Since the phase speed satisfies c p = λ/T = λf, wavelength and period (or frequency) are related. For instance in deep water:
The speed of propagation of a wave is equal to the wavelength divided by the period, or multiplied by the frequency: v = λ τ = λ f . {\displaystyle v={\frac {\lambda }{\tau }}=\lambda f.} If the length of the string is L {\displaystyle L} , the fundamental harmonic is the one produced by the vibration whose nodes are the two ends of the ...
An electromagnetic wave travels in a direction that is at right angles to the oscillation direction of both fields. In the 19th century, James Clerk Maxwell showed that, in vacuum, the electric and magnetic fields satisfy the wave equation both with speed equal to that of the speed of light.
The wave equation describing a standing wave field in one dimension (position ) is p x x − 1 c 2 p t t = 0 , {\displaystyle p_{xx}-{\frac {1}{c^{2}}}p_{tt}=0,} where p {\displaystyle p} is the acoustic pressure (the local deviation from the ambient pressure) and c {\displaystyle c} the speed of sound , using subscript notation for the partial ...
Signal velocity is usually equal to group velocity (the speed of a short "pulse" or of a wave-packet's middle or "envelope"). However, in a few special cases (e.g., media designed to amplify the front-most parts of a pulse and then attenuate the back section of the pulse), group velocity can exceed the speed of light in vacuum, while the signal ...