# Uses of Wien's law of displacement Wiens's displacement law says <mrow class="MJX-TeXA

Uses of Wien's law of displacement
Wiens's displacement law says
${\lambda }_{\text{max}}T=\text{a constant}$
So if I have the ${\lambda }_{\text{max}}$, I can find the temperature of a star. But if I have the temperature, is there any point in calculating ${\lambda }_{\text{max}}$? What information does that give us of the star, besides temperature?
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Allyson Gonzalez
So, let's start with the formal definition of peak wavelength. Peak wavelength $\left({\lambda }_{max}\right)$ is the wavelength where an object absorbs the most photons (or, to our eyes, becomes more dark, or, at a darker point, completely isn't in the visible spectrum. (for a refresher, take a look at the electromagnetic spectrum, and here's something to look at as you go: electromagnetic spectrum)
Well, back to your question, why do we even have ${\lambda }_{max}$, and what is it used for? So, I did a bit of research in an astrochemistry textbook that I have, and found a reason why peak wavelength is useful. It is useful as a parameter to compare the quality of several types of molecules.