Which law states, The radiant energy emitted by a black body per unit area per unit time is directly proportional to the fourth power of its absolute temperature.

PHYSICS

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Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]

Which law states, “The radiant energy emitted by a black body per unit area per unit time is directly proportional to the fourth power of its absolute temperature".

A	Stefan’s Law
B	Doppler’s Effect
C	Kirchhoff’s Law
D	Newton’s law of cooling

Explanation:

Detailed explanation-1: -According to Newton’s law of cooling, the rate of cooling of a body is directly proportional to the temperature difference between the body and the surroundings.

Detailed explanation-2: -Derivation of Newton’s Law of Cooling from Stefan’s Law: Let e be the emissivity (or coefficient of emission) of the surface of the body. Let (T-To) = x, where x is Small. ∴ T = To + x. Where E & Eb, are the emissive powers of the body and perfectly black body respectively.

Detailed explanation-3: -Fourier’s law states that the negative gradient of temperature and the time rate of heat transfer is proportional to the area at right angles of that gradient through which the heat flows. Fourier’s law is the other name of the law of heat conduction.

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GENERAL KNOWLEDGE

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PHYSICS