Black body radiation Definition and 161 Threads

taking a lump of coal as an approximation of a black body, what is the explanation for the phenomenon of the emitted light changing colour from red to white when it is heated, ie the emitted quanta themselves changing, rather than simply more being released.

I came across a formula that gives radiant energy density as 4 * sigma * T^4 / c. I am trying to figure out how this formula follows from Stefan-Boltzmann law. Shouldn't it be 4*pi instead of just 4? I am also wondering why one can just stick in c. TIA

I was looking over the calculation leading to the thermal average number of photons s in a mode of frequency w in a black body. The approach was pretty straightfoward: Calculate the partition function Z based on quantized energies of a harmonic oscillator, then use this to calculate: <s> \ = \...

Homework Statement 1)The peak emission from a black body at a certain temperature occurs at a wavelength of 9000 Angstrom. On increasing its temperature the total radiation emitted is increased 81 times. At the initial temperature, when the peak radiation from the black body is incident on a...

Sir, A polished metal plate with a rough black spot on it is heated to about 1400 Kelvin and quickly taken into a dark room. It is said that the black spot will appear brighter than the plate. Is it because the black spot is a perfect black body and hence is a better absorber of heat than...

Hi, I found one very interesting physics problem but I have no idea how to solve it. Lets say we have a star with radius R and the surface temperature T. Now we wish to know, what is the ratio between the total power output of the star and the power that the distant planet receives from...

can i ask ... how could Planck's idea of quantised energy explain the ultraviolet catastrophe? WHAT is being quantised? the oscillator atoms of the blackbody cavity? or? thanks

If the sun at temperature 6000K emits onto an asteroid 350million km away, what is the temperature of the asteroid assuming it is a black body? Any suggestions how to go about this please? :confused: :confused:

My problem is that I have the numbers...but I don't have a formula. "The sun's temp. is about 6000 K, it's radius 700000 km. How much power is it radiating? If there is no dissipation between here and the sun, how much of this hits the earth?" Is this the P = c/4*U thing?

Hello, New to this message board (and very happy to have found it). I am reading a book on cosmology by Steven Weinberg... I am having a terrible time understanding what exactly black body radiation is. Could someone please describe it in the most accesible terms? Also, if you would please...

why can't classcial mechanic explain black body radiation?