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  1. "he continuous emission spectrum is due to the surface temperature of the Sun. According to the Bohr model, light of a specific frequency is emitted due to the difference of two energy states of one (? or a few) element. Why a white hot iron bar can emit white light?
  2. The spectrum of sunlight is a continuous spectrum as in the rainbow. But superimposed on the spectrum are dark absorption lines of some specific frequencies. From the absorption lines, we are able to tell that the main elements of the sun is hydrogen, iron, carbon, helium and some others. My question is why the continuous spectrum ? Elements have characteristic emission line spectra. So every specific wavelength in the sun's continuous spectrum is associated with one (?) element which has that wavelength in its line spectrum. Does it mean that the sun has all 108+ known elements? [edit] Or the emission lines of the main elements in the sun - iron,carbon, etc. - sufficient to form the continuous spectrum.
  3. Yes.This Steiner paper exactly satisfy what I am looking for. It gave the first value of h to around end 1910. It also gave the method used to measure h historically, basically the photoelectric effect in the earlier years. I am not able to access any peer reviewed articles. Thanks. I posted the same question over physics stack exchange. Because they can't give me the information, they insist that there is no reason for me to to look for such information as the "different values should not be comparable". At other time physics stackexchange do give good answers.
  4. It would probably mean you and I are not up-to-mark to view those papers.
  5. I looked all over to get the various accepted value of the Planck constant since 1900. But there is never any record about the history of this mysterious number.
  6. You may say so. But if Bragg's method can be used for all gamma ray, does it not bypass the relation E=hν. What if there is a method so "direct" that it requires 99 more relation in between? Can Bragg's method be used for all gamma rays?
  7. Bragg's law : nλ = 2d Sinθ relates wavelength of x-rays "directly" to angle. I consider this direct. Can this be used for all gamma rays. In E=hf, we need to assume an energy to frequency relation and so it is "indirect."
  8. Then, I will re-phrase. Measuring gamma ray frequencies without using energy detector and E=hf. Then what about those outside of the possible "some" ranges; the higher known frequencies.
  9. I know there are ways to measure light frequencies directly using diffraction, etc, even for x-rays. Is there a way to directly measure the frequency of gamma rays? Not using energy detectors and E=hf.
  10. Say if I have a laser beam. If I shine another laser beam to intersect the first beam, will this first beam be affected?
  11. This is only about a redefinition of some SI units such as the kilogram. With whatever changes in the SI units, the atomic mass will still be measured through mass spectrometry. When mass spectrometry was invented after the 1910, they only go for greater improvements to get higher resolution. There is no published experiment that anyone made any independent verification if mass spectrometry is reliable. Our current analytical balance is accurate to 10¯⁵, enough to make chemical analysis of relative atomic mass of compounds composed of single isotopes of the elements. A simple example is sodium iodide; both elements exist as stable single isotope in nature.
  12. Has there been any experiment done through chemical analysis to check if mass spectrometry is consistent with our chemical balance? Our current analytical balance has an accuracy of 10¯⁵. The chemical composition by weight of two isotopes forming a compound could be analyzed. This is sufficient to determine a relative atomic mass of two isotopes and to compare with the CODATA values obtained through mass spectrometry. The values should be the same to at least the third decimal. This is a very good test of the reliability of mass spectrometry. We have about 19 monoisotopic elements including Fluorine and Iodine; these two may react with the other monoisotopic elements to form compounds.
  13. What you get is only the classical atomic weights. In nature H has 0.02% deuterium. O has O16, O17 and O18 in various %. So the old atomic weights is a mixture of isotopes. We need H₂O that is made from pure isotope ¹H and pure isotope ¹⁶O. Only then can we get real relative atomic mass to compare with the CODATA obtained from mass spectrometry..
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