How do you define wave speed

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  • #1
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say for example there is a pulse through a string .then what exactly is wave speed or for that matter in case of unidirectional wave motion
 

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  • #2
russ_watters
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Could you rephrase the question....I'm not sure what you are asking. Are you asking what determines the speed of a wave? If so, the answer is the tension and elastic modulus of the string.
 
  • #3
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how do u define wave speed
 
  • #4
ZapperZ
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What's wrong with [itex]v=f\lambda[/itex]?

Zz.
 
  • #5
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i want to have the definition well the espression is well one perhaps a physical interpretation will do
 
  • #6
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Well, you get a wave, and look at how fast the peaks and troughs are moving.
 
  • #7
ZapperZ
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i want to have the definition well the espression is well one perhaps a physical interpretation will do

Could you say that again and maybe, this time, include a few punctuations?

Zz.
 
  • #8
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Sorry i didn't realize that how difficult is it to read that line without punctuation.
Could u please define Wave speed in general mathematically
 
  • #9
f95toli
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There is no general definition for the speed of a "wave" if you by "wave" also mean pulses etc.

*The velocity at which a plane wave would propagate through a medium [tex]c[/tex] this is a constant which depends on properties of the medium (e.g. the speed of light or the speed of sound)

*Phase velocity, [tex]v_p=\omega/\beta[/tex], is the speed at which a constant phase point (i.e. a maximum) travels. [tex]\beta[/tex] is the propagation constant.

*Group velocity [tex]v_g=(d\beta/dt)^{-1}[/tex], is the speed at which a signal (such as a pulse) propagates thorugh a medium. This is only a meaninfull concept for signals with a narrow bandwidth or in media with low dispersion.

Note that you can have [tex] v_p>c[/tex].
 

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