# Kirchhoff's law

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Related to Kirchhoff's law: Kirchhoff's current law, Kirchhoff's first law

## Kirchhoff's law

[′kərk‚hōfs ‚lȯ]
(electricity)
Either of the two fundamental laws dealing with the relation of currents at a junction and voltages around closed loops in an electric network; they are known as Kirchhoff's current law and Kirchhoff's voltage law.
(thermodynamics)
The law that the ratio of the emissivity of a heat radiator to the absorptivity of the same radiator is the same for all bodies, depending on frequency and temperature alone, and is equal to the emissivity of a blackbody. Also known as Kirchhoff's principle.
References in periodicals archive ?
However, Robitaille points out that the above definition of Kirchhoff's Law is not complete and furthermore Robitaille maintains that the statement above should be called Stewart's Law as it was originally propounded by Stewart in 1858 [13]: "All too frequently, the simple equivalence between apparent spectral absorbance and emission is viewed as a full statement of Kirchhoff's law, .
Furthermore based on Kirchhoff's law, the emissivity in a certain polarization is equal to the absorptivity with the same polarization, which can be expressed as
Given all that is involved relative to the validity of Kirchhoff's Law [1,2], Robert Johnson is to be commended, as the first duty of a scientist is to defend established science against possibly false charges.
Recently, the author has proposed two gedanken experiments in order to revisit Kirchhoff's law [15,16].
Moreover, because of Kirchhoff's law and the associated insistence that the radiation within a cavity must be independent of the nature of the walls, a tremendous void is created in the understanding of thermal emission.
The physics community currently maintains that, under these conditions, both cavities must contain black radiation, in accordance with Kirchhoff's law [1,2], despite the fact that the second cavity, being fully adiabatic, acts as a perfect reflector and, hence, is unable to emit a single photon.
First, the condition under which Kirchhoff's law is often presented, the perfectly absorbing cavity, can be considered (emissivity ([member of]) = 1, absorptivity ([kappa]) = 1, reflectivity ([rho]) = 0; at the frequency of interest, v).
In reality, it would not be an overstatement to argue that Kirchhoff's law [15,16] constitutes the very core of accepted solar theory.
The problems with Kirchhoff's law were not simple to identify [61-66] and Planck himself [67, 68] echoed Kirchhoff's belief in the universal nature of radiation under conditions of thermal equilibrium [69, p.
Like Schuster before him, Schwarzschild based his conclusion on the validity of Kirchhoff's law [9].
Instead, Milne, like Schuster [12], Schwarzschild [13], and Eddington [14-17] before him, automatically presumed that the invocation of Kirchhoff's law provided sufficient proof that the interior of the Sun harbored black radiation, despite the absence of the rigid enclosure required by Kirchhoff [10].

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