Kirchhoff's Law of Radiation

 In accordance with Kirchhoff's law (Assume transmissivity $a_t\to 0$ for all the cases)

With an increase in wavelength, the monochromatic emissive power of a black body

 The absorptivity of black body equals to

If radiant energy E _B emitted by the black surface strikes the non-black surface. If non-black surface has absorptivity α, it will absorb how many radiations?

 If two surfaces are at the same temperature, then the conditions correspond to mobile thermal equilibrium for which the resultant interchange of heat is zero are

State Kirchhoff's law of radiation and prove it theoretically.

A planet of radius $R_p$ is revolving around a star of radius $R^{*}$, which is at temperature $T^{*}$. The distance between the star and the planet is $d$. If the planet's temperature is $f{T}^{\star }$, then $f$ is proportional to

Relation between emissivity $e$ and absorptive power $a$ is (for black body)
 

State Kirchhoff’s law of radiation.

State:

Kirchhoff's law of radiation. 

"Spectral line of the emission is same as that of the absorption" is the statement of

The temperatures of two bodies $A$ and $B$ are $727°\mathrm{C}$ and $327°\mathrm{C}$, respectively. The ratio $H_{\mathrm{A}}:H_{\mathrm{B}}$ of heat radiated by the bodies is

Assertion: When a green glass is heated in a furnace and taken out, it is found to glow with red light.

Reason: Red and green are complementary.

A body has same temperature as that of the surrounding. Then

Three objects coloured black, gray and white can with stand hostile conditions at $2800°\mathrm{C}$. These objects are thrown into furnace where each of them attains a temperature of $2000°\mathrm{C}.$ Which object will glow brightest?

"Good emitters are good absorbers" is a statement concluded from

From Kirchhoff's law the ratio of emissive power and absorption power of all bodies -

Two bodies $A$and $B$ having temperatures 327$℃$ and 427$℃$ are radiating heat to the surrounding. The surrounding temperature is 27$℃$ . The ratio of rate of heat radiation of $A$ to that of $B$ is

Two spheres of radii 8 cm and 2 cm are cooling. Their temperatures are 127$℃$ and 527$℃$ respectively. Find the ratio of energy radiated by them in the same time

"Good emitters are good absorbers" is a statement concluded from