Is black body always black?
No radiation passes through it and none is reflected, yet in classical physics, it can theoretically radiate any possible wavelength of energy. Despite the name, black bodies are not actually black as they radiate energy as well.
What is a black body Class 11?
A black body is an idealization in physics that pictures a body that absorbs all electromagnetic radiation incident on it irrespective of its frequency or angle.
What is black body answer?
An object that absorbs all radiation falling on it, at all wavelengths, is called a black body. When a black body is at a uniform temperature, its emission has a characteristic frequency distribution that depends on the temperature. Its emission is called black-body radiation.
What is emissive power and absorptive power?
When heat is incident on the surface of the body some of the heat is absorbed while other is reflected. Emissive power : ” the energy of thermal radiation emitted in all directions per unit time from each unit area of a surface at any given temperature” acobdarfq and 21 more users found this answer helpful.
What factors does the emissive power of a body depends?
So, we can say that emissive power depends on temperature and wavelength.
Why is a mirror an example of a poor black body radiator?
Detailed balance, i.e. 2nd law of thermodynamics, requires a relationship between absorbing incoming radiation and turning it into heat, versus emitting thermal radiation. A perfect mirror at rest does not absorb any incoming radiation, therefore it is a “whitebody”, not a blackbody, and emits no thermal radiation.
Why is Earth a black body?
The Earth climate system maintains a balance between solar energy absorbed and IR (blackbody) energy radiated to space. The so-called Greenhouse effect distributes the temperature in the atmosphere so that the surface is much warmer than the mean radiative temperature.