black body
Definition
- Noun:
- A theoretical, perfect absorber and emitter of radiation: A "black body" is a hypothetical, idealized physical object that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. Because it absorbs all radiation, it is also a perfect emitter of thermal radiation. The spectrum and intensity of the radiation it emits depend solely on its temperature.
Examples of Usage
- Noun:
- In physics, a black body is used as a standard model to understand thermal radiation.
- The concept of a black body was crucial in the development of quantum mechanics.
- No real object is a perfect black body, but a closed oven with a small hole is a very close approximation.
Advanced Usage
- "Black-body radiation": The characteristic electromagnetic radiation emitted by a black body in thermal equilibrium.
- The study of black-body radiation led Max Planck to propose the idea of quantized energy.
- "Black-body spectrum": The specific distribution of wavelengths or frequencies of the radiation emitted by a black body at a given temperature.
- The Sun's emission spectrum closely resembles a black-body spectrum at approximately 5,800 Kelvin.
Variants and Related Words
- Blackbody (adj/noun): A common alternative spelling, often used as a compound adjective (e.g., blackbody radiation, blackbody curve).
- Cavity radiator (noun): A practical device, like a hollow object with a small hole, that approximates the behavior of a black body.
- Perfect emitter (noun): A descriptive term for one of the key properties of a black body.
- Planckian locus (noun): The path or curve that the color of a black body traces in a color space as its temperature changes.
Synonyms
- Ideal radiator: Emphasizes its perfect emission properties.
- Full radiator: A term used in the reference definition, indicating it radiates energy at the maximum possible rate for its temperature.
Related Concepts (Not Phrasal Verbs or Idioms)
- Stefan-Boltzmann law: States that the total energy radiated per unit surface area of a black body is proportional to the fourth power of its absolute temperature.
- Wien's displacement law: Describes how the peak wavelength of black-body radiation shifts with temperature.
- Ultraviolet catastrophe: A historical problem in classical physics predicting infinite ultraviolet radiation from a black body, which was resolved by quantum theory.
Noun
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a hypothetical object capable of absorbing all the electromagnetic radiation falling on it
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a black body maintained at a constant temperature is a full radiator at that temperature because the radiation reaching and leaving it must be in equilibrium
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