Wikipedia:Reference desk/Archives/Science/2024 February 4

= February 4 =

Planck'law and stefan-Boltzmann law relation
In a forum I found that the relation between the Stefan-Boltzmann law and the Planck law in the black body cavity hole is: $$B=T^4\sigma=\int_{\lambda=0}^\infty\pi B _{\lambda(\lambda,T)}d\lambda$$ Is that true, or is there a different equation ? Malypaet (talk) 13:42, 4 February 2024 (UTC)
 * See Stefan–Boltzmann_law, where the integral is written in terms of frequency rather than wavelength. --Wrongfilter (talk) 13:52, 4 February 2024 (UTC)
 * Thanks for the link, I understand better. Malypaet (talk) 09:21, 5 February 2024 (UTC)

Organic Nomenclature
I've been unable to find the name of the CH2= group, I suspect it might be methenyl. So what would be the preferred IUPAC name for 2-ethylbut-1-ene. Taabibtaza (talk) 14:34, 4 February 2024 (UTC)
 * Hey, I'm not a chemist, but AIUI IUPAC rule P2 gives methylidene for CH2=, so I'd suggest 3-methylidene pentane for CH3.CH2.C(:CH2).CH2.CH3 which is what I think you're after for CH2:C(C2H5).CH2.CH3 HTH, Martin of Sheffield (talk) 15:12, 4 February 2024 (UTC)
 * @Taabibtaza IUPAC naming conventions are a minefield. For this sort of question, I'd use Chemspider and look at the various possibilities. See this entry for 2-ethyl-1-butene which they say is alternatively called 3-methylenepentane. IUPAC wouldn't use methylidene in the case of simple alkenes where the double bond is the only functional group. Mike Turnbull (talk) 17:13, 4 February 2024 (UTC)