Tagged Questions
3
votes
2answers
43 views
Black body radiation
I have a few questions related to the emission of electromagnetic radiation by black bodies. Consider the following image:
On the above image I have drown the rays of light that are emmited by ...
5
votes
1answer
58 views
Temperature of glowing materials
As I understand it, Stars emit visible light, OBAFGKMRNS, in the range of $10^3 - 10^4 K$.
Yet materials such as steel emit similar frequencies at much lower temps; red is around 800K.
Why the ...
1
vote
1answer
60 views
Electromagnetic field to cool a substance?
I saw somewhere that an electromagnetic field would cause a substance to let off thermal energy, ultimately resulting in the substance to cool really quickly.
If this is possible, does the strength ...
11
votes
6answers
640 views
What are the various physical mechanisms for energy transfer to the photon during blackbody emission?
By conservation of energy, the solid is left in a lower energy state following emission of a photon. Clearly absorption and emission balance at thermal equilibrium, however, thermodynamic equilibrium ...
2
votes
0answers
146 views
Classical blackbody radiation 'solution'
I never understood how the equipartition theorem was applied electromagnetic waves inside the metallic blackbody. As hyperphysics puts it ...
2
votes
3answers
217 views
Why aren't the graphs for black body radiation straight lines?
We know that a wave which has greater frequency will have low wavelength and high energy. So, by decreasing the wavelength, the frequency and consequently energy (intensity) of that wave will increase ...
2
votes
1answer
100 views
Commercial Infrared lights
I purchased an infrared light. It's a 100 W Philips infrared lightbulb. Says it's infrared, but I haven't done any spectrum analysis so I don't know for sure if it's just red or really infrared.
As I ...
0
votes
2answers
214 views
Radiated power and energy density for a black-body
I am having an hard time trying to understand why the radiated power per unit area $P$ of a black body is given by
$$P=\frac{c}{4} u$$
in terms of the energy density $u$ and the velocity of light.
I ...
0
votes
4answers
841 views
How to get Intensity over a range of wavelengths from a Total Intensity
This is a theory vs experiment problem for me I think in that - as usual - I think I know the theory, but when it comes time to run an experiment, I can't actually extract squat.
So, here is my light ...
3
votes
2answers
257 views
How might a resonant antenna and black body radiation interact?
How does an antenna behave when it is cooled so that its black-body radiation is emitting energy at its resonant frequency?
Edit: To clarify, its not how they're related in general, but how might ...
5
votes
4answers
1k views
Light emitted by an object according to its temperature
According to this picture
the light emitted by an object depends on its temperature.
That makes perfect sense when we heat a metal. As its temperature raises we see it red at first, then orange, ...
6
votes
3answers
4k views
Why do lightbulbs continue to glow after the light is turned off?
I've noticed that whenever I turn the lamp off in my room at night, the lightbulb seems to continue to glow for a minute or so after that. It's not bright though; the only way I even notice it is if ...
6
votes
1answer
629 views
What’s the relationship between thermal radiation and Johnson thermal noise?
All objects above absolute zero emit radiation due to random collisions between the atoms they are made of. The spectrum of radiation emitted varies according to the temperature of the object, I ...
