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Difference between dispersive medium and nondispersive medium. 
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#1
Nov2911, 12:34 PM

P: 184

Hello experts!
I have 2 questions. 1)Difference between dispersive and nondispersive medium. 2)ω=[itex]\sqrt{\frac{4β}{m}}[/itex]sin[itex]\frac{Ka}{2}[/itex] is a relation for dispersive medium. How to reduce it to nondispersive relation? Here is some math work I have performed to reduce it to nondispersive relation i.e. At low frequency K→0 so, sin([itex]\frac{Ka}{2}[/itex])→[itex]\frac{Ka}{2}[/itex] so the equation becomes, ω=[itex]\frac{2}{a}[/itex]ν_{s}[itex]\frac{Ka}{2}[/itex] or, ω=ν_{s}K where, ν_{s} is phase velocity. So ω=ν_{s}K is the relation for nondispersive medium? Is it? Thanks in advance. 


#2
Dec1111, 12:46 PM

P: 1,521

ν_{s}(k) = [itex]\frac{ω(k)}{k}[/itex] Group velocity (if of interest) is instead the derivative: ν_{g}(k) = [itex]\frac{dω(k)}{dk}[/itex]. 


#3
Dec1111, 01:15 PM

P: 184

Late reply.
But you are the only one up till now who replied me. So thanks for reply. β is spring constant. It is come from the derivation of 1D monoatomic. m is the mass of the atoms. You mean ω=v_{s}k is not for the nondispersive medium? 


#4
Dec1111, 06:14 PM

P: 1,521

Difference between dispersive medium and nondispersive medium.



#5
Dec1311, 01:52 PM

P: 184

Oh great
Thanks a lot. Best answer. Thanks. And one thing I want to say you that kindly, visit this solid state portion at least once a week but try it every week. Because only you are here to answer the post. No one else. Thanks once again. 


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