What is the second radiation constant?
The second radiation constant is c_2 = 1.438776877e-2 m·K, exact by SI definition. It appears in Planck's blackbody law and Wien's law.
Open the interactive PhysRef tool →Key facts
| Value | 1.438776877e-2 m·K |
|---|---|
| Symbol | c_2 |
| Relation | c_2 = h·c/k_B |
| Exactness | Exact by SI definition (uncertainty 0) |
| Source | CODATA 2018 |
Frequently asked questions
What is the value of the second radiation constant?
c_2 = 1.438776877e-2 m·K, appearing in Planck's law and linking Wien's displacement constant.
How is c_2 defined?
c_2 = h·c/k_B, combining the Planck constant, speed of light, and Boltzmann constant.
Is the second radiation constant exact?
Yes, because h, c, and k_B are all exact, c_2 is exact.
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