Wien's Law Peak Wavelength Tool

Wien's displacement law states that the peak wavelength of radiation emitted by a blackbody is inversely proportional to its absolute temperature: λ_max = b/T. This constant b is approximately 2.8978 × 10⁻³ m·K, derived from Planck's radiation law. The displacement reflects the transition of energy states: as a star or object heats up, its thermal energy density increases, shifting the peak of its spectral emission toward shorter, more energetic wavelengths (from infrared to visible light and ultraviolet).

This tool turns the everyday link between color and temperature into a number. Everyday intuition runs backwards: on a tap, red means hot and blue means cold, but for glowing objects it is the reverse. A cool body glows dull red; heat it and the peak slides through orange, yellow, and finally blue-white. That is why the red star Betelgeuse (~3500 K) is far cooler than blue-white Rigel (~12000 K).

Wien's law has a hidden trap: the wavelength where a blackbody peaks and the frequency where it peaks do not describe the same photon. The Sun's spectrum peaks near 500 nm in wavelength (green), yet its frequency spectrum peaks around 880 nm (infrared). They differ because squeezing wavelength into frequency stretches the axis unevenly. So the 'peak frequency' this tool reports, ν = c/λ_max, is not where the frequency curve actually maxes out.