Sound vs Light

[GomerPyle]

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I understand that light travels slower in denser material (and it always remains at constant velocity in a given material). Once light is created, that frequency will never change, regardless of medium.

With sound, the velocity is always constant unless the material changes. If you move into more dense material, the velocity increases, but how come it moves faster in warmer air, which is less dense than colder air?

Also - does v = f*lambda apply to sound, or just light? What about frequency and wavelength of sound?

Thx.

 

[FeinMS]

Velocity of sound does depend on the Temperature.
According to TBR Chapter 6, Velocity of a sound in gas= sqrt(gamma*Pressure/density)=sqrt(gamma*R*Temperature/Molar Mass) where Gamma is Cp/Cv. It also shows that the sound travels slower in higher density gas. However, note that the sound travels faster in solids and liquids which is denser than gas. There's a little bit of confusing relationship. V=f*lambda applied to both light and sound.

 

[GomerPyle]

Velocity of sound does depend on the Temperature.
According to TBR Chapter 6, Velocity of a sound in gas= sqrt(gamma*Pressure/density)=sqrt(gamma*R*Temperature/Molar Mass) where Gamma is Cp/Cv. It also shows that the sound travels slower in higher density gas. However, note that the sound travels faster in solids and liquids which is denser than gas. There's a little bit of confusing relationship. V=f*lambda applied to both light and sound.

okay so that explains why it travels slower in cooler, more dense air. Thanks!