Wien Displacement Constant

Relates a blackbody's temperature to its peak emission wavelength — why hotter objects glow bluer.

Specifications & Metrics

symbol

b

status

Exact — derived from defining constants

value

0.002897771955 m·K

Relative Scale in Constants

Core Principles & Analysis

• Wien's law λ_max = b/T locates a blackbody's brightest wavelength.
• A 5,772 K Sun peaks near 502 nm, green light; the 2.725 K cosmic microwave background peaks near 1.06 mm.
• Derived from h, c, and k_B, it became exact along with them in the 2019 redefinition.

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