Talk:Wien approximation

Old discussion
I'm not familiar enough with the subject matter to say -- on RC patrol, I ran into this user, who added this to the article. Several of their edits today have appeared questionable -- anyone care to comment? Luna Santin 19:45, 9 October 2006 (UTC)

Article name
This function is not consistently referred to by the same name in physics textbooks, although "Wien's law" seems to be used more frequently than other names (despite the ambiguity of the name with Wien's displacement law). Several users in a Jan 2007 discussion at Wikipedia Talk:WikiProject Physics decided to use "Wien approximation" as the title for this article. Note, however, that a move in the future may be appropriate. Dr. Submillimeter 13:20, 15 January 2007 (UTC)


 * Dr. S, good work on fixing up this article. Thanks: --Sadi Carnot 12:19, 25 January 2007 (UTC)


 * I was under the impression that Wien Approximation more commonly refers to Wien's Displacement Law. Dr. S, think this page would be better named as "Wien Distribution"?  That's what it was linked as when I first reached it. --Keflavich 20:12, 8 May 2007 (UTC)


 * I think Wien Distribution Law might be OK, but it should probably be discussed more first. I suggest starting a new discussion at Wikipedia Talk:WikiProject Physics or placing a post there to direct people to a discussion here.  Dr. Submillimeter 07:01, 9 May 2007 (UTC)


 * I would like to change the title of the page to Wien's law. If you have a reason why this should not occur, I am happy to 'talk' about it. Regards, Grahamwild (talk) 10:16, 22 February 2009 (UTC)

There's something wrong!
The article tells right in the beginning, that "The law may be written as":

$$I(\nu, T) = \frac{2 h \nu^3}{c^2} e^{-\frac{h \nu}{kT}}$$

and just beneath that "This equation may also be written as":

$$I(\lambda, T) = \frac{2 h c^2} {\lambda^5} e^{-\frac{hc}{\lambda kT}}$$

Obviously noone encountered so far, that you don't get the 2nd from the 1st. Replacing the $$\nu$$ by $$c/\lambda$$ would lead to:

$$I(\lambda, T) = \frac{2 h c} {\lambda^3} e^{-\frac{hc}{\lambda kT}}$$

As references are cited for both equations, one has to be wrong!


 * This is not a case where it is as simple as replacing $$\nu$$ by $$c/\lambda$$. $$I(\nu, T)$$ is a derivative of $$\nu$$, whereas $$I(\lambda, T)$$ is a derivative of $$\lambda$$.  Note that $$d\nu = -(c/\lambda^2)d\lambda$$.  When this is taken into account, the two equations should be equal.  Dr. Submillimeter 08:05, 19 July 2007 (UTC)


 * Those are two different functions. First is distribution for frequency and the other is that for wavelength. The functions are integrated over different variables so only the value of integration is supposed to be same for these two. EditingPencil (talk) 09:53, 3 November 2023 (UTC)

Alternate Derivation
This is something that has been annoying me for a while. It is a fact that Planck's radiation formula was derived years after Wien's law. Given that, why do all of the online sources derive Wien's law using a high frequency limit of Planck's formula? What I think is necessary is the addition of a derivation without the use of Planck's formula. 68.231.22.246 (talk) 21:32, 26 April 2010 (UTC)

Wien approximation wrong!
The Wien approximation is given in millimeters, but the source uses cgs, or centimeters, and the numeric value is not adjusted accordingly. It would be better to stay in SI units (meters). Please cross reference with http://hyperphysics.phy-astr.gsu.edu/hbase/wien.html#c2 or better, derive it yourself.

107.200.73.249 (talk) 10:32, 22 October 2012 (UTC)Tom

Seems odd
It seems odd that this article doesn't reference the Stefan–Boltzmann_law law. Beowulf (talk) 14:51, 25 September 2020 (UTC)

Minus
Is this a kind of bug? In some (not in all) of the formulas of this article, the minusses are not shown although they are clearly there in source code. Maybe, you can understand what I mean, if you compare this:

I(\nu, T) = \frac{2 h \nu^3}{c^2} e^{-\frac{h \nu}{kT}} ,


 * $$I(\nu, T) = \frac{2 h \nu^3}{c^2} e^{-\frac{h \nu}{kT}} ,$$

with this:

I(\nu, T) = \frac{2 h \nu^3}{c^2} e^{\bf{-}\frac{h \nu}{kT}} ,


 * $$I(\nu, T) = \frac{2 h \nu^3}{c^2} e^{\bf{-}\frac{h \nu}{kT}} ,$$

The only difference in the code is boldfont for the minus in the second version. I see the minus in the second formula, but not in the first. The minus appears only if I zoom in extremely.

If this is a bug it is quite annoying. It cost me half an hour of my lifetime to understand how the function can converge for high frequencies. Even worse would be to accept the formula without minus thoughtlessly. --Pyrrhocorax (talk) 22:19, 13 January 2021 (UTC)

Wien's Approximation
Why does Wien's approximation not redirect to this article? 173.225.242.134 (talk) 15:52, 29 May 2022 (UTC)

Correct maxima for Wien's approximation
The maxima for Wien's approximation were added to this article in 2012. (https://en.wikipedia.org/w/index.php?title=Wien_approximation&oldid=471882064) However, the maxima given were actually for Planck's law and not Wien's approximation. These maxima are already covered in the Wien's displacement law article. I do not have the Irwin (2007) book that is cited as the source for these equations. It's likely that the reference discusses Wien's displacement law and not the maxima calculated from Wien's approximation.

I have corrected the maxima to be consistent with Wien's approximation. However, it may be more appropriate to remove the maxima and cross reference to Wien's displacement law instead. 65.60.153.214 (talk) 17:40, 27 January 2023 (UTC)