Drupe skrev:
Varme er et udtryk for hvilken hastighed partikler bevæger sig med. Når noget er varmt bevæger molekylerne i genstanden sig hurtigere. Varme ting har det med at udsende EM-stråling, og det er det der udnyttes i night-vision kameraer - de kan opfange EM-stråling der ligger uden for det spektre øjet kan opfatte.
Vi snakker vist forbi hinanden drupe
Jeg snakker om el-pærer og udnyttelsen af deres energi til at skabe synlighed. Og i den forbindelse er varme EM-stråling.
http://electron4.phys.utk.edu/141/oct31/October%2031.html skrev:
Atoms in molecules and solids are held together by chemical bonds. Chemical bonds are electromagnetic in origin, but can be modeled well by tiny springs
Dér begynder det. Vibrationer i det EM-felt der holder partiklerne sammen.
http://electron4.phys.utk.edu/141/oct31/October%2031.html skrev:
Two atoms held together by a spring have an equilibrium position. If they are pushed closer together, they repel each other. If they are pulled farther apart, they attract each other. If they are displaced in any way from their equilibrium position and then released, they start vibrating about their equilibrium position. A atom can form different chemical bonds with a variety of other atoms. Different bonds are represented by springs with different spring constants. The stiffer the spring, the more work it takes to pull the atoms apart. If enough work is done, then the spring is stretched too much and it breaks, i.e. the chemical bond breaks.
At room temperature all atoms in a solid vibrate about their equilibrium position. If work is done which increases their kinetic energy, the amplitude of the vibrations increases, and eventually the chemical bonds break. Most free atoms quickly form new bonds. If the new bonds are stronger, i.e. the new springs are stiffer, they do more work pulling the atom to their new equilibrium positions than was needed to break the old bonds. This work is converted into random kinetic energy, i.e. thermal energy. Thermal energy is released by a chemical reaction. The temperature increases.
Altså EM-energi forklaret som små fjedre der holder atom-delene sammen. Atom-delene vibrerer i forhold til hinanden, og påvirker dermed den EM-fjeder der holder delene sammen. I dette samlede system opbevares varme-energien, som du nævner. Men før vi ka' se den, ska' den jo ud-stråles, og det er så dén varme jeg talte om.
http://electron4.phys.utk.edu/141/oct31/October%2031.html skrev:
Nuclei and electrons are charged particles. When charged particles accelerate, the emit electromagnetic radiation and loose energy. Vibrating particles are always accelerating since their velocity is always changing. They therefore always emit electromagnetic radiation.
Så en varm el-pære udstråler altså altid EM-stråling, og dén varme er EM-stråling.
http://en.wikipedia.org/wiki/Heat skrev:
Thermal radiation is a direct result of the movements of atoms and molecules in a material. Since these atoms and molecules are composed of charged particles (protons and electrons), their movements result in the emission of electromagnetic radiation, which carries energy away from the surface. ...
For room temperature objects (~300 K), the majority of photons emitted (and involved in radiative heat transfer) are in the infrared spectrum, but this is by no means the only frequency range involved in radiation. The frequencies emitted are partially related to black-body radiation. Hotter objects - a light bulb filament at 3000K for instance - transfer heat in the visible spectrum or beyond.
Måske burde jeg ha' forklaret det mere udspecificeret i min første post, men jeg ville undgå at den blev for lang, så det var et kompromis.
Og for lige at rette op på en fejl, hvor du ganske rigtigt fangede mig på det forkerte ben, er her et billede af infra-røde, almindeligt synlige og ultra-violette frekvenser
UV er kort, infra-rød er langt.
Så har vi vist fået det hele på plads
Undtaget om det ku' være en mulighed at gen-splejse mennesker til at være følsomme overfor infra-rødt lys for at spare lys-energi?
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