Duduli

According to prevost, every body emits radiations continuously to its surroundings at the rate which depends only on the nature of its surface and temperature and at the same time it receives radiations from its surroundings at the rate depending on the surface and the temperature of surroundings.

The sun consists of a central hot portion surrounded by the photosphere.The central portion has a temperature of the order of 10⁷K.The photosphere has a temperature of about 6000K which is calculated  by considering the sun as a perfect black body radiator.

Radiation is the method of heat transfer in which the heat flows from position of higher temperature to that of lower temperature without the aid of medium.In radiation, the heat flows by means of electromagnetic waves.For their propagation, no medium is required.If medium is present, it does not absorb heat. Therefore, radiation may take place in vacuum also.Heat from the sun reaches the earth by radiation.

Answer:- It states that the rate of emission of radiant energy by unit area of a perfectly black body is directly proportional to the fourth power of its absolute temperature.

Answer:- It is the amount of heat energy (radiation) absorbed per minute by the sq. cm of a perfectly black body surface placed at a mean distance of the earth from the sun, in the absence of the atmosphere, the surface being held perpendicular to the sun's rays.