Blackbody

Definition

A blackbody is an idealized object that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. It also emits radiation at a characteristic spectrum that depends only on its temperature.

5 Must Know Facts For Your Next Test

1. A perfect blackbody does not reflect any light; it appears completely black at room temperature.
2. The radiation emitted by a blackbody is known as blackbody radiation and follows Planck's Law.
3. The peak wavelength of blackbody radiation shifts to shorter wavelengths as the temperature increases, known as Wien's Displacement Law.
4. Blackbodies are used as a reference standard for color temperature in lighting and imaging applications.
5. Stars are often approximated as blackbodies to model their emission spectra and determine their temperatures.

Review Questions

• What law describes the shift in peak wavelength of a blackbody's emitted radiation with temperature?
• Why is a perfect blackbody considered an ideal absorber and emitter of radiation?
• How do astronomers use the concept of a blackbody to understand the properties of stars?

Related terms

Planck's Law:

Describes the spectral density of electromagnetic radiation emitted by a blackbody in thermal equilibrium at a given temperature.

Wien's Displacement Law:

States that the wavelength at which the emission of a blackbody spectrum is maximized is inversely proportional to its temperature.

Stefan-Boltzmann Law:

Indicates that the total energy radiated per unit surface area of a blackbody is directly proportional to the fourth power of its absolute temperature.