What is a black body? Explain black body radiation.

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Black Body And Black Body Radiation

Black object (BLACK BODY) is that which completely absorbs all those radiations. Radiations that fall on or incident to them, irrespective of whether they are colored or colorless, the black objects neither reflect nor transmit them.

This is the reason why black objects always appear in black (black) color. BLACK BODY can also be called a complete radiator or a complete radiator.

All objects that are heated to a high temperature radiate energy, with the maximum being the energy radiated by the black object (BLACK BODY).  Hence dark objects are called complete radiators.

Radiation emitted by black objects is called BLACK BODY RADIATION.

The energy radiated per unit area by the black object (BLACK BODY) depends on the temperature of the black object (BLACK BODY), but the wavelength of the radiations emitted at a certain temperature is not the same wavelength.

( black body radiation curves )

The spectrum of radiations emitted by a black object (BLACK BODY) at a certain temperature is evident from the spectrum (Fig. 1.1). That this diagram shows the correlation between energy density and the emitted wavelength at a certain temperature (6000K).

The spectrum (curve) of the wavelength of radiations emitted by a black body (BLACK BODY) at a certain temperature has the following characteristics -

1. The energy or intensity of radiations emitted by BLACK BODY at a certain temperature is not uniform, but the energy emitted at a certain wavelength is the highest for a given temperature.  In the picture it is shown from point A.

2. Different spectrums of this type are obtained at different temperatures. (As in Figure 1.2)

3. The total energy emitted by a black object varies according to the temperature of that object. (As in Figure 1.2)

4. The highest (max) becomes more pronounced at higher temperatures and with the increase in temperature the position of the highest (max) is shifted to the region of shorter wavelength.