Infra-red Electromagnetic waves.

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Discussion Overview

The discussion revolves around the nature of infra-red electromagnetic waves, their relationship to temperature, and the mechanisms of heat transfer. Participants explore concepts related to thermal radiation, the behavior of molecules at different temperatures, and the interactions of light with matter.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants express confusion about the relationship between temperature and infra-red radiation, questioning how molecular motion relates to the emission of infra-red photons.
  • Others clarify that small molecules emit energy as infra-red photons, which correlates with a decrease in temperature as energy is lost.
  • It is noted that radiation is one of the three forms of heat transfer, with all matter emitting radiation as it cools, and that the peak emission wavelength shifts with temperature.
  • Some participants argue that infra-red light is not uniquely related to heat, as all types of light are forms of electromagnetic radiation, but the emission of hot objects peaks in the infra-red range.
  • Questions are raised about why hotter objects emit more radiation at shorter wavelengths and whether this is influenced by chemical composition or physical properties.
  • There is a discussion about the nature of collisions between particles and how these contribute to radiation, with some suggesting that higher energy collisions produce higher energy photons.
  • Concerns are expressed about the distinction between heating by atomic collisions versus heating by photon absorption, and whether all heat is related to electromagnetic forces.

Areas of Agreement / Disagreement

Participants do not reach a consensus, as there are multiple competing views regarding the mechanisms of heat transfer, the relationship between temperature and radiation, and the nature of light's interaction with matter.

Contextual Notes

Some limitations include unresolved assumptions about the definitions of heat and light, the dependence of emission peaks on various factors, and the complexity of interactions at the quantum level.

GrizzlyBat
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I understand that they come from objects with high temperature. But to me it makes no sense because from what I understand temperature is measuring the small molecules moving around, I do not see where the relationship is between the two. Do I have an idea mixed up?
 
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The small molecules moving around give off energy in the form of infra red photons. This means they have less energy, so move around less, so the temperature of the object drops.
 
It's one of the three forms of heat transfer, radiation. All matter with heat gradually emits radiation and cools (unless it absorbs more than it emits). The greater the temperature the more radiation and higher the frequency. Infrared light is no more related to heat than any other type of light (radio, visible, x-ray, gamma). It just so happens that objects with temperatures we would normally call hot have their emission peak in infrared.

http://en.wikipedia.org/wiki/Thermal_radiation
 
elctromagnetic waves are transverse in nature. not affected by electric and magnetic field.
 
dave_baksh said:
The small molecules moving around give off energy in the form of infra red photons. This means they have less energy, so move around less, so the temperature of the object drops.

DaleSwanson said:
It's one of the three forms of heat transfer, radiation. All matter with heat gradually emits radiation and cools (unless it absorbs more than it emits). The greater the temperature the more radiation and higher the frequency. Infrared light is no more related to heat than any other type of light (radio, visible, x-ray, gamma). It just so happens that objects with temperatures we would normally call hot have their emission peak in infrared.

Is there a reason why the objects with "hot" temperatures have there emission peak in the infrared? Does the emission peak depend mostly on the chemical composition or physical nature of the object? If all light is heat, is there a difference between absorption and emission of light and heat transfer, or are they synonymous? Don't different frequencies of light affect matter in different ways (affecting different electron energy levels and the nucleus of atoms, molecular torsion, reflecting off, scattering off) instead of just causing them to heat up (random motion) regardless of frequency? Do all of these interactions of matter with light occur at the quantum level? I'm confused on how all light causes heating , but the effects on matter can be so drastically different.

Thank you
 
The radiation comes not from the motion of the particles, but rather their colissions with each other. In a warmer object, the colissions are of higher energy, allowing higher energy photons to be produced. This is what moves the peak to shorter wavelength radiation as temperature increases.
 
see Blackbody radiation. I wouldn't say "hot" objects emit in the infrared that's pretty low energy. Things that are about room temperature emit in the infrared, you get hotter like a lightbulb and you get yellow, you get even hotter like certain types of blow torches, you get way hotter like the surface of a star and you get UV-cosmic depending on the layer.
 
flatmaster said:
The radiation comes not from the motion of the particles, but rather their colissions with each other. In a warmer object, the colissions are of higher energy, allowing higher energy photons to be produced. This is what moves the peak to shorter wavelength radiation as temperature increases.

Is the collision between two atoms mediated by a photon? Or else, it would seem that there would be a discrepancy between heating by collisions between atoms and heating by absorption of photons by atoms. Is all heat related to the em force?

Thank you for your responses
 

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