absorbance

Thân thiện

A scientist measures the absorbance of a blue liquid sample.

Definition

Noun (Physics): A logarithmic measure of the amount of light or other electromagnetic radiation that is absorbed by a substance. It is calculated as the logarithm of the ratio of incident radiant power to transmitted radiant power through the substance.

Usage

"Absorbance" is a scientific term used primarily in physics and chemistry to quantify how much light a material prevents from passing through it. A higher absorbance value indicates that more light is being absorbed.

Examples

• The spectrophotometer measured the absorbance of the sample at 450 nanometers.
• According to Beer's Law, the absorbance of a solution is directly proportional to its concentration.
• The graph plots absorbance versus wavelength to identify the compound.

Advanced Usage

• Molar Absorptivity: This is a related concept. Absorbance (A) is equal to the molar absorptivity (ε) times the path length (l) times the concentration (c), expressed in the Beer-Lambert law: A = εlc.
• Optical Density (OD): In some contexts, particularly in microbiology, "absorbance" is used interchangeably with "optical density" to measure the concentration of cells in a liquid culture.

Variants and Related Words

• Absorb (verb): To take in or soak up (energy, a liquid, etc.).
  • The dark fabric absorbs more heat.
• Absorptance (noun): The ratio of absorbed radiant flux to incident radiant flux. While related, "absorptance" is a different, dimensionless measure.
• Transmittance (noun): The fraction of incident light that passes through a substance. Absorbance is the negative logarithm of transmittance.

Synonyms

• Optical Density (OD)
• Extinction (in specific contexts)

Antonyms

• Transmittance
• Transparency

Học thuật

Noun

1. (physics) a measure of the extent to which a substance transmits light or other electromagnetic radiation

Từ đồng nghĩa

• optical density
• transmission density
• photographic density