Black body can be made by:
Correct answer: B. A hollow cavity within a solid body
- A. A surface coated with lamp black
- B. A hollow cavity within a solid body
- C. A highly polished black body
- D. A tungsten filament
Explanation
A black body, in theory, is an idealized object that absorbs all incident electromagnetic radiation. While it's impossible to create a perfect black body, some objects approximate its behavior under certain conditions. A cavity with a small opening can act as a good approximation of a black body. The radiation inside the cavity reflects multiple times, and after sufficient reflections, it becomes nearly independent of the material of the cavity walls.
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About Dawn of Modern Physics
Classical physics cannot explain blackbody radiation and related observations, leading to Planck’s quantum theory, in which energy is emitted or absorbed in discrete packets. Photons provide the particle model of light, with energy and momentum linked to frequency and wavelength, including the photoelectric effect and its threshold frequency.
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