Talk:Planck's law

Symbol for spectral radiance

The symbol for spectral irradiance used in the Wikipedia article of the same name is L not B. L is also the ISO 80000 recommended symbol for this quantity. This article should use L instead of B for consistency.

Equation errors?

It looks to me as though there are errors in at least one of the six "Different forms" equations. When I tried using the form that used wavelength instead of frequency, my answers were ridiculous. I'm not an expert so I don't want to change anything for fear of being mistaken, however a simple substitution of nu = c / lambda in the first equation yields an answer quite different than the equation right below it. I'm hoping someone knowledgeable will see this and take a look. 47.14.123.228 (talk) 18:23, 20 April 2023 (UTC)

There is no error. It is not the spectral densities that are equal to each other, but rather their integrals. For this reason e.g. frequency and wavelength forms are related by

$$B_{\lambda }(\lambda ,T)=-{\frac {d\nu }{d\lambda }}B_{\nu }(\nu (\lambda ),T),$$

which includes a factor from the change of variables. The relation between the different forms is discussed in the text after the table. Jähmefyysikko (talk) 18:59, 20 April 2023 (UTC)

Thanks for the clarification. I understand. 47.14.123.228 (talk) 14:47, 26 April 2023 (UTC)

Another Equation Error?

In the fractional bandwidth form for Planck's function, the numerator of the second factor is x⁴. I think it ought to be x³. The integral of Planck's function w.r.t. ν is the Stefan-Boltzmann law, and the coefficient of T⁴ after integration is the Stefan-Boltzmann constant σ. With the numerator being x⁴, the constant is wrong, and contains a factor of ζ(5). With the numerator being x³ the constant after integration is the Stefan-Boltzmann constant. — Preceding unsigned comment added by Van.snyder (talk • contribs) 04:02, 5 November 2023 (UTC)

its distribution with respect to ln(x) so you have an extra x. EditingPencil (talk) 03:16, 6 November 2023 (UTC)

Also constants follow from Planck's spectral radiance law for frequency. B_ln(x) = B_nu d(nu)/d(lnx). Please don't mind my lazy reply ;p EditingPencil (talk) 03:22, 6 November 2023 (UTC)

Bibliography for "Planck, M. (1901)" link not yet available

In Bibliography for "Planck, M. (1901)", as original Ando file is not yet available,

I propose to add a link to a new translated version on wikimedia, which respects as faithfully as possible the form of the german original:

https://upload.wikimedia.org/wikipedia/commons/4/4e/On_the_Law_of_the_Energy_Distribution_in_the_Normal_Spectrum.pdf

(https://commons.wikimedia.org/wiki/File:On_the_Law_of_the_Energy_Distribution_in_the_Normal_Spectrum.pdf) Malypaet (talk) 21:47, 18 October 2023 (UTC)

Typo on graph

It seems there is a typo error on the ordinate-axis of the spectral radiance graph, namely, numeral 22 should be 2 and numeral 44 should be 4. Esem0 (talk) 06:03, 2 January 2024 (UTC)

Planck's law of black-body radiation

Can I add this note in the page

https://duckduckgo.com/?t=ffab&q=black-body+radiation

He discoverd this on October 19 1900... but not noted in the page Scottsdesk (talk) 22:31, 21 August 2024 (UTC)