Wien Displacement Law

A blackbody does not emit the same amount of radiation at all wavelengths; its spectrum has a single peak that shifts as the temperature changes. Wien Displacement Law says that as temperature increases, the peak moves to shorter wavelengths, because hotter objects populate higher-energy electromagnetic modes more strongly. The constant b is an empirically measured constant that comes out of the full blackbody radiation spectrum derived from quantum theory.

Use this law when you want to estimate the temperature of an object from the wavelength where its emission is strongest, such as stars, planets, dust clouds, or heated lab objects. It is also useful for predicting whether the peak will lie in infrared, visible, or ultraviolet light.

• Using the temperature in Celsius instead of Kelvin
• Confusing the peak wavelength with the wavelength where the object looks brightest to the eye
• Forgetting that the formula gives the peak of the spectrum, not the total emitted power