Wien's displacement law

The AP Physics 2 CED calls it Wien's law, without the word displacement, so both names lead to the same statement. Essential knowledge 15.4.A.3.ii: the peak wavelength emitted by a blackbody, meaning the wavelength at which it emits the greatest amount of radiation per unit wavelength, decreases with increasing temperature.

Printed in the Modern Physics group of the AP Physics 2 sheet. The constants table lists Wien's constant as $b = 2.90 \times 10^{-3}\ \mathrm{m \cdot K}$, and $T$ is in kelvin.

Read the word peak precisely. It marks the maximum of intensity per unit wavelength plotted against wavelength (15.4.A.3), not the only wavelength present. A blackbody emits a continuous spectrum, and this law says where that spectrum is tallest.

Inverse, and only inverse. Double the temperature and the peak wavelength halves. A body at $2900\ \mathrm{K}$ peaks at $(2.90 \times 10^{-3})/2900 = 1.0 \times 10^{-6}\ \mathrm{m}$, in the infrared. At $5800\ \mathrm{K}$ the peak sits at $5.0 \times 10^{-7}\ \mathrm{m}$, inside the visible band.

It answers a different question from its partner. Wien's law moves the peak sideways along the wavelength axis; the Stefan-Boltzmann law gives the total power leaving the surface. Heating a body does both at once, and a question describing a change of colour wants this one.