heat

[psicicle]

how is heat transmitted through a vacuum? If heat is the vibration of particles, then how can it travel through no medium? When heat is transmitted through particles, is it transmitted by infared light?

[swansont]

how is heat transmitted through a vacuum? If heat is the vibration of particles, then how can it travel through no medium? When heat is transmitted through particles, is it transmitted by infared light?

 

EM radiation of any wavelength, not just IR.

 

When it's transmitted through particles, it's because the particles have kinetic energy.

[5614]

EM radiation is made of photons which are energy, which is where the energy transfer comes from.

 

As Swansont said althought traditionally heat is IR, that is not always the case.

[psicicle]

oh... I have another question: since heat is moving atoms, then if you heat something enough then would you get sound?

[swansont]

oh... I have another question: since heat is moving atoms, then if you heat something enough then would you get sound?

 

Intersting question. Sound is compression waves, which implies some coherence, and the motion associated with temperature is random and follows a continuous distribution of speeds, so there is no identifiable vibration frequency. So generally, no. But I think there may be exceptions, where the structure of the material had resonances, and the restriction of the vibration modes might give you sound. And other possible exceptions I haven't though of. So I'd have to say I think it's possible under the proper conditions.

[Johnny5]

Originally Posted by psicicle

oh... I have another question: since heat is moving atoms' date=' then if you heat something enough then would you get sound? [/quote']

 

Intersting question. Sound is compression waves, which implies some coherence, and the motion associated with temperature is random and follows a continuous distribution of speeds, so there is no identifiable vibration frequency. So generally, no. But I think there may be exceptions, where the structure of the material had resonances, and the restriction of the vibration modes might give you sound. And other possible exceptions I haven't though of. So I'd have to say I think it's possible under the proper conditions.

 

Swanson, can you be more specific about the proper conditions. You mentioned that there would be no clear vibration frequency. My question is this. Is one of the conditions that the object have an oscillatory and rapid temperature change? Rapid expansion and contraction kind of thing?

[swansont]

Swanson, can you be more specific about the proper conditions. You mentioned that there would be no clear vibration frequency. My question is this. Is one of the conditions that the object have an oscillatory and rapid temperature change? Rapid expansion and contraction kind of thing?

 

No, the scenario I was envisioning is steady state, but the vibration modes are somehow limited for the material. I have no actual example in mind; I don't think the scenario is likely, but I also don't think the answer to the question is a definite no. I know that phonon modes are quantized, so that would be a start, and the question becomes whether you could get a banding behavior like in electronic levels.

 

Rapid, repeated heating or cooling would do it as well, but the oscilliatory nature of the heat transfer is the source of the sound. Certainly thermal expansion of a gas through a small orifice works, e.g. a teakettle.

[Johnny5]

No' date=' the scenario I was envisioning is steady state, but the vibration modes are somehow limited for the material. I have no actual example in mind; I don't think the scenario is likely, but I also don't think the answer to the question is a definite no. I know that phonon modes are quantized, so that would be a start, and the question becomes whether you could get a banding behavior like in electronic levels.

 

Rapid, repeated heating or cooling would do it as well, but the oscilliatory nature of the heat transfer is the source of the sound. Certainly thermal expansion of a gas through a small orifice works, e.g. a teakettle.[/quote']

 

Thank you.