What is a black body and what are its characteristics?
A black body is an idealized object that absorbs all electromagnetic radiation (light) that falls on it, and at thermal equilibrium, it also emits radiation with a continuous spectrum. Some of the characteristics of a black body are:
1. Perfect absorbance: It absorbs all the radiation that falls on it, irrespective of the frequency or wavelength of the radiation.
2. Continuous spectrum: It emits radiation with a continuous spectrum, which means it emits radiation at all wavelengths.
3. Emissive power: It emits radiation with a maximum emissive power at a specific wavelength, which is related to its absolute temperature.
4. Ideal thermal radiator: It is an ideal thermal radiator, as it absorbs and emits radiation according to the laws of thermodynamics.
5. Constant emissivity: The emissivity of a black body is constant, independent of temperature and wavelength.
6. Maximum emissivity: The emissivity of a black body is always maximum than any other object.