# Rate of emission from a black body

• Lakshya
In summary, a black body is an object that absorbs all light and emits thermal radiation at all wavelengths. The rate of emission is the amount of thermal radiation emitted per unit time and surface area, and can be calculated using the Stefan-Boltzmann law. This rate is directly proportional to the temperature of the black body and varies with wavelength according to Planck's law.
Lakshya
What is the proof that the total rate at which radiation is emitted by a black-body radiator is proportional to the fourth power of the temperature? Does this result come from Planck's radiation law? If yes, how?

timthereaper said:

Thank you very much. :)

## 1. What is a black body?

A black body is an idealized object that absorbs all wavelengths of light without reflecting or transmitting any. It is also a perfect emitter of thermal radiation at all wavelengths.

## 2. What is the rate of emission from a black body?

The rate of emission from a black body refers to the amount of thermal radiation emitted per unit time and per unit surface area. It is also known as the black body radiation or Planck's law.

## 3. How is the rate of emission from a black body calculated?

The rate of emission from a black body can be calculated using the Stefan-Boltzmann law, which states that the total power emitted per unit surface area is proportional to the fourth power of the absolute temperature of the object. The constant of proportionality is known as the Stefan-Boltzmann constant.

## 4. Does the rate of emission from a black body depend on its temperature?

Yes, the rate of emission from a black body is directly proportional to its temperature. As the temperature of the black body increases, the rate of emission also increases.

## 5. How does the rate of emission from a black body vary with wavelength?

The rate of emission from a black body varies with wavelength according to the Planck's law, which describes the spectral distribution of the emitted radiation. It shows that the rate of emission is higher at shorter wavelengths and decreases as the wavelength increases.

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