How does heat transfer take place?

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SUMMARY

Heat transfer occurs through three primary mechanisms: conduction, convection, and radiation. Conduction involves the transfer of heat through direct contact between molecules, while convection refers to the movement of heat through fluids, and radiation involves the emission of infrared waves from a warm body. Heat energy is defined as energy in transfer, not a substance, and is fundamentally linked to the kinetic motion of molecules. Photons, which are massless particles of light, can cause heat by increasing molecular motion when absorbed, but they are not heat themselves.

PREREQUISITES
  • Understanding of kinetic theory and molecular motion
  • Familiarity with the concepts of conduction, convection, and radiation
  • Basic knowledge of electromagnetic waves, particularly infrared radiation
  • Awareness of quantum mechanics and the nature of photons
NEXT STEPS
  • Research the principles of heat transfer in thermodynamics
  • Explore the kinetic theory of gases in detail
  • Learn about the properties of electromagnetic radiation, focusing on infrared waves
  • Study the role of photons in energy transfer and quantum mechanics
USEFUL FOR

This discussion is beneficial for students of physics, engineers working with thermal systems, and anyone interested in the fundamental principles of heat transfer and energy dynamics.

manogyana25
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I'm having a problem with understanding how energy flows from one body to the other.

So gases at high pressure travel towards low pressured areas. So there is a reason behind this. Since molecules of gases have the tendency to move away from each other, they travel towards low pressured areas. So molecules are the paticles that comprise all the matter.
So what is heat energy comprised of? Are there any particles in it? Why does it travel from a hotter body to a colder body??
 
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Heat energy comes from the speed of those molecules. The more they bump off of each other, the hotter the substance.
 
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There are three forms of heat transfer: convection, radiation, and conduction. Google them.
 
Your answer is what heat is made of and if it comprises of particles?
I can only say you that it isn't a substance: in past one believed it was a form of matter like fluid but then it was discovered that in a solid object after heat transfer there wasn't an appreciable decrease of mass. Now it is defined as a energy in transfer.
Kinetic theory explains at a microscopic level how this transfer take place: matter is made of particles like molecules which get this energy; the disordered motion of the molecules in gases or their vibrations in solids , which are due to heat, generates heat exchanges among this particles.
Another way of transfer, we've seen, is radiation: here the heat is emitted from an emitting surface of a warm body as infrared, an electromagnetic wave, and then it is absorbed by a receiving surface.
 
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Blackberg said:
Heat energy comes from the speed of those molecules. The more they bump off of each other, the hotter the substance.

Then what are photons actually??
 
Pierce610 said:
Your answer is what heat is made of and if it comprises of particles?
I can only say you that it isn't a substance: in past one believed it was a form of matter like fluid but then it was discovered that in a solid object after heat transfer there wasn't an appreciable decrease of mass. Now it is defined as a energy in transfer.
Kinetic theory explains at a microscopic level how this transfer take place: matter is made of particles like molecules which get this energy; the disordered motion of the molecules in gases or their vibrations in solids , which are due to heat, generates heat exchanges among this particles.
Another way of transfer, we've seen, is radiation: here the heat is emitted from an emitting surface of a warm body as infrared, an electromagnetic wave, and then it is absorbed by a receiving surface.
Thanks a lot! That was a good explanation. But I came to know that light contains mas less particles called photons. Light is a form of energy, right? Then why doesn't heat energy have those particles?
 
manogyana25 said:
Thanks a lot! That was a good explanation. But I came to know that light contains mas less particles called photons. Light is a form of energy, right? Then why doesn't heat energy have those particles?
You might want to give some thought to what sunlight is.
 
manogyana25 said:
Thanks a lot! That was a good explanation. But I came to know that light contains mas less particles called photons. Light is a form of energy, right? Then why doesn't heat energy have those particles?
I'm nice to help you; but I'm not an expert and so I can't tell you...
 
Pierce610 said:
I'm nice to help you; but I'm not an expert and so I can't tell you...
No, you don't have to say that you aren't an expert sir. You helped me a lot, so thank you once again Mr. Pierce610.. :smile::smile::smile:
 
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manogyana25 said:
Then what are photons actually??
Photons are quantum objects. If you measure them for wave properties, they will show wave properties but they are not classical waves. If you measure them for particle properties, they will show particle properties, but they are not classical particles. They are quantum objects. Period.
 
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  • #11
manogyana25 said:
Then what are photons actually??

a. When a molecule absorbs a photon, it moves faster. That is heating through radiation.
b. When molecules bump into each other as I dryly stated, that is heating by conduction.
c. When a moving molecule is brought somewhere else, that is heating by convection.

When I say "moving", that includes rotation, vibration, and going somewhere else.

So photons can cause heat, with a. above, but photons "are" not heat. Photons cause heat by causing molecules to move when absorbed.
 

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