Definition

1. Noun:
   • (Physics): The property of a body that determines the fraction of the incident radiation or sound flux that is absorbed by the body. It is a measure of how much energy a material absorbs compared to what it receives.

Usage Examples

• Noun:
  • The absorptivity of the black paint is very high, making it ideal for solar collectors.
  • Scientists measured the material's absorptivity across different wavelengths of light.

Advanced Usage

• "Spectral absorptivity": Refers to absorptivity measured at a specific wavelength or across a range of wavelengths.
  • The spectral absorptivity of the glass changes in the infrared range.
• "Thermal absorptivity": Often used in the context of a material's ability to absorb heat radiation.
  • The thermal absorptivity of the ceramic coating improves the oven's efficiency.

Variants and Related Words

• Absorbance (n): In analytical chemistry, a logarithmic measure of the amount of light absorbed by a substance. Related to but distinct from absorptivity.
• Absorption coefficient (n): A measure of how easily a material absorbs radiation per unit distance; closely related to absorptivity.
• Absorptive (adj): Having the ability or tendency to absorb.
  • The absorptive qualities of the sponge are excellent.

Synonyms

• Absorption factor: A term sometimes used interchangeably with absorptivity.
• Absorptive power: An older or more general term for the capacity to absorb.

Notes on Meaning

• Physics vs. General Use: In physics and engineering, "absorptivity" is a precise, quantitative property. In more general contexts, it is rarely used; the simpler noun "absorption" is preferred.
• Relation to Emissivity: In thermodynamics, for a body in thermal equilibrium, its absorptivity at a given wavelength equals its emissivity at that same wavelength (Kirchhoff's law of thermal radiation).

Noun

1. (physics) the property of a body that determines the fraction of the incident radiation or sound flux absorbed or absorbable by the body