Search results
Results From The WOW.Com Content Network
Value [a] [b] Relative standard uncertainty Ref [1] speed of light in vacuum 299 792 458 ... first radiation constant for spectral radiance
Consequently, these terms can be considered as physical constants themselves, [19] and are therefore referred to as the first radiation constant c 1L and the second radiation constant c 2 with c 1 L = 2 hc 2
Radiation constant may refer to: The first and second radiation constants c 1 and c 2 – see Planck's Law; The radiation density constant a – see Stefan ...
first radiation constant: c 1 = 3.741 771 852... × 10 −16 W⋅m 2: u r (c 1) = 0 [27] c1L: first radiation constant for spectral radiance: c 1L = 1.191 042 972... × 10 −16 W⋅m 2 ⋅sr −1: u r (c 1L) = 0 [28] c2: second radiation constant: c 2 = 1.438 776 877... × 10 −2 m⋅K: u r (c 2) = 0 [29] sigma: Stefan–Boltzmann ...
Planck was able to calculate the value of from experimental data on black-body radiation: his result, 6.55 × 10 −34 J⋅s, is within 1.2% of the currently defined value. [2] He also made the first determination of the Boltzmann constant from the same data and theory. [14]
As 2.57 4 = 43.5, it follows from the law that the temperature of the Sun is 2.57 times greater than the temperature of the lamella, so Stefan got a value of 5430 °C or 5700 K. This was the first sensible value for the temperature of the Sun. Before this, values ranging from as low as 1800 °C to as high as 13 000 000 °C [25] were claimed.
A physical constant, sometimes fundamental physical constant or universal constant, is a physical quantity that cannot be explained by a theory and therefore must be measured experimentally. It is distinct from a mathematical constant , which has a fixed numerical value, but does not directly involve any physical measurement.
c 1 = 2 π hc 2 is the first radiation constant c 2 = hc/k is the second radiation constant. and M is the black body spectral radiant exitance (power per unit area per unit wavelength: watt per square meter per meter (W/m 3)) T is the temperature of the black body h is the Planck constant c is the speed of light k is the Boltzmann constant