Wien's displacement law: the wavelength where a black body glows brightest falls as it gets hotter. The Sun (about 5800 K) peaks near 500 nm.
Value of b in different units
| Value | Use it when |
|---|---|
| 2.898 × 10⁻³ m K | SI. |
| 0.29 cm K | CGS, in older books. |
Formulas that use b
- λₘₐₓ T = b
Its dimensional formula is worked out on the dimensional formula of wien's constant b page.
Other constants
- Gas constant (R): 8.314 J mol⁻¹ K⁻¹
- Planck's constant (h): 6.626 × 10⁻³⁴ J s
- Avogadro's number (Nₐ): 6.022 × 10²³ mol⁻¹
- Speed of light (c): 3 × 10⁸ m/s
- Charge of an electron (e): 1.602 × 10⁻¹⁹ C
- Mass of an electron (mₑ): 9.109 × 10⁻³¹ kg
- Mass of a proton (mₚ): 1.673 × 10⁻²⁷ kg
- Mass of a neutron (mₙ): 1.675 × 10⁻²⁷ kg
- Universal gravitational constant (G): 6.674 × 10⁻¹¹ N m² kg⁻²
- Acceleration due to gravity (g): 9.8 m/s²
- Boltzmann constant (k): 1.381 × 10⁻²³ J/K
- Faraday constant (F): 96 485 C/mol
- Permittivity of free space (ε₀): 8.854 × 10⁻¹² C² N⁻¹ m⁻²
- Permeability of free space (μ₀): 4π × 10⁻⁷ T m/A
- Rydberg constant (R): 1.097 × 10⁷ m⁻¹
- Stefan–Boltzmann constant (σ): 5.67 × 10⁻⁸ W m⁻² K⁻⁴
- Wien's constant (b): 2.898 × 10⁻³ m K
- Bohr radius (a₀): 0.529 Å
- Molar volume of a gas at STP (Vₘ): 22.4 L/mol
The full list, searchable, is on the physical constants page.
Questions students ask
What is the value of Wien's constant?
b = 2.898 × 10⁻³ m K. In other units: 2.898 × 10⁻³ m K; 0.29 cm K.
What is b in physics and chemistry?
Wien's displacement law: the wavelength where a black body glows brightest falls as it gets hotter. The Sun (about 5800 K) peaks near 500 nm.
Which value of b should I use?
2.898 × 10⁻³ m K: SI. 0.29 cm K: CGS, in older books.
What is the dimensional formula of Wien's constant?
See the dimensional formula of Wien's constant, worked out step by step on its own page.