Constants of spectral radiation of uniformly heated inclosure, or so-called Black Body, I
1914; The National Institute of Standards and Technology; Volume: 10; Issue: 1 Linguagem: Inglês
10.6028/bulletin.224
ISSN2376-8991
Autores Tópico(s)Numerical methods in inverse problems
ResumoConstants of Spectral Radiation 3 obtain the spectral energy curve free from atmospheric absorption bands.This will be the crucial test to determine the form of the energy curve.One of the causes of disagreement in the results obtained by present-day experimenters is owing to the method of computation (Planck or Wien equations) employed in the reduc- tion of the observations.With the optical path in a vacuum there is no objection to having a focal length of several meters for the objective mirror, thus increasing the dispersion and hence removing one of the present objections to the use of a fluorite prism.This is especially desirable when working at high tem- peratures.Using a larger dispersion it will be possible to determine the constants with greater precision by both the isothermal and the isochromatic curves.This no doubt will require a redetermination of the refractive indices of fluorite.It may seem somewhat belated to question the prevailing notion that the form of the spectral energy curve has been thor- oughly estabHshed.However, when one inquires thoroughly into the matter it is found that there is hardly a single piece of experi- mental work that stands the present-day criteria for deciding whether either one of the formulae, Wien's or Planck's, fits the experimental observations.In the earUer work of Paschen,^the Wien equation seemed to agree with the experimental results.Bulletin of the Bureau of Standards [Voi.w published data purporting to prove that the Planck equation fitted the observed energy curves, but, as will be mentioned elsewhere, this was made decisive by multiplying the observed curves, beyond 3.9/^, by arbitrary factors, which did not appear to seri- ously affect the computations of the constants.The comments made at that time, by Lummer and Pringsheim,^were to the effect that the results were not a satisfactory proof of the Planck equation.About the only precise work done at that period was that of Rubens and Kurlbaum,^who examined the residual rays (9 to
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