Quantum Physics Confusion: Black Bodies & Spectrums

Click For Summary

Discussion Overview

The discussion revolves around the concepts of black body radiation and the spectrum of the Sun, including the origins of solar radiation and the meaning of spectral lines. Participants explore theoretical aspects of quantum physics, particularly in relation to black body behavior and absorption spectra.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Homework-related

Main Points Raised

  • One participant questions the source of the original radiation absorbed by the Sun, distinguishing it from the emitted radiation.
  • Another participant expresses confusion about the meaning of "white lines" on a spectrum and the claim that the spectrum does not extend beyond visible light.
  • A response suggests that the Sun's energy originates from fusion at its core, proposing a conceptual analogy of the outer layer absorbing light from the core, while noting the complexity of energy transport within the Sun.
  • A participant seeks clarification on the concept of peak wavelength in black body radiation, noting that black bodies emit energy across all wavelengths but exhibit a peak at a specific wavelength.
  • Discussion includes the historical context of black body radiation, mentioning Planck's resolution of the ultraviolet catastrophe and the significance of the Planck distribution in understanding the peak wavelength.
  • Another participant explains that the absorption spectrum of the Sun is determined by the specific molecules and atoms in its atmosphere, which absorb certain frequencies of light.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and confusion regarding the concepts discussed. There is no consensus on the original source of solar radiation or the interpretation of spectral lines, indicating multiple competing views and unresolved questions.

Contextual Notes

Some participants express uncertainty about specific terms and concepts, such as "white lines" on a spectrum and the peak wavelength, highlighting the need for further clarification and exploration of these topics.

Who May Find This Useful

This discussion may be useful for students studying quantum physics, particularly those interested in black body radiation and the spectral characteristics of stars, as well as individuals seeking to clarify foundational concepts in these areas.

ehabmozart
Messages
212
Reaction score
0
Well, am an Alevel student... Edexcel.. I just find quantum physics a really really confusing topic.. My question is particularly in black bodies. If we consider the sun as a black body, where did the radiations of the sun initially come from. I don't mean the emitted radiation we see, i mean the original radiation which it absorbed. Secondly, what do white lines on a spectrum means and why yhe spectrum doesn't reach beyond visible light.. I am new to this forum so forgive my way I've posted my doubt.. Thanks :D
 
Physics news on Phys.org
Guys.. I really need help cs am having a test in a couple of weeks and i understand nothing!
 
The Sun gets its energy from fusion at its core. I suppose you can think of it kind of like the outer layer of the sun "absorbing light" from the core if it helps you conceptualize a little better (of course, don't take it too literally, there's a complex energy transport problem from the inner to outer regions of the sun which involves a lot more than just radiation transfer).

I don't know what you mean by "white lines" on a spectrum. What are you referring to? Are you talking about absorption and emission lines from the Sun? Also, what do you mean "the spectrum doesn't reach 'beyond' visible light"? The Sun radiates at all frequencies, it just mostly radiates in the visible because those are the frequencies corresponding to the peak in the black-body curve for the Sun (it is probably for this reason that we evolved to see visible light).
 
Dude, i owe u.. Thanks for help.. Here are my current doubts... What is a peak wavelength.. Like, a black body emits energy of all wavelenghts but y is there a peak at a particular one.. Secondly, it was mybad, i just wanted to know the absorption spectrum..
 
The black body radiation gives a peak, this was one of the fundamental results of Planck and his distribution. To really understand the reason why there's a peak, one needs to understand the Planck distribution.

For example, before Planck, Rayleigh had a "black body solution"; however, it ran into the Ultraviolet catastrophe. It was Planck who solved this problem by "quantizing" the energy (somewhat arbitrarily) of the atoms in a black body.

The absorption spectrum of the Sun is dictated by what molecules and atoms are in the Sun's atmosphere. Certain molecules/atoms will absorb certain frequencies of light. When the light from the Sun's photosphere is being transported through its atmosphere, some of it is absorbed by these molecules/atoms at those specific frequencies. There's not much more to it than that.
 

Similar threads

  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 12 ·
Replies
12
Views
2K
  • · Replies 6 ·
Replies
6
Views
2K
  • · Replies 7 ·
Replies
7
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 23 ·
Replies
23
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 25 ·
Replies
25
Views
2K