planck's law

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planck's law

A scientist explains Planck's law using a diagram of energy quanta.

Definition

Noun: 1. A fundamental law of quantum mechanics: Planck's law states that electromagnetic energy is emitted or absorbed in discrete, indivisible packets called quanta (or photons), rather than as a continuous wave. The energy (E) of a single quantum is directly proportional to the frequency (ν) of the radiation: E = hν, where h is Planck's constant. 2. Specifically for blackbody radiation: More narrowly, Planck's law refers to the mathematical formula that describes the spectral density of electromagnetic radiation emitted by a black body in thermal equilibrium at a given temperature. This formula resolved the ultraviolet catastrophe problem in classical physics.

Usage Examples
  • General Principle: Planck's law introduced the revolutionary concept that energy is quantized.
  • Historical Context: The formulation of Planck's law marked the birth of quantum theory.
  • Scientific Application: To calculate the energy of a photon of blue light, one must apply Planck's law.
Advanced Usage
  • "Derive Planck's law": To mathematically obtain the formula from fundamental principles of quantum statistics and electromagnetism.
    • In advanced thermodynamics, students learn to derive Planck's law for blackbody radiation.
  • "In accordance with Planck's law": Behaving or calculated in a way that follows this fundamental principle.
    • The photoelectric effect operates in accordance with Planck's law.
Variants and Related Words
  • Planck constant (h) (n): The fundamental physical constant (approximately 6.626 × 10⁻³⁴ J·s) appearing in the formula of Planck's law, representing the proportionality factor between the energy of a photon and its frequency.
  • Planck's radiation law (n): A full synonym, often used specifically for the blackbody radiation formula.
  • Quantization (n): The core concept introduced by Planck's law, meaning that a physical quantity can have only certain discrete values.
Synonyms
  • Planck radiation law
  • Law of energy quantization (descriptive synonym for the general principle)
Related Phrases
  • To obey/follow Planck's law: Used to describe a physical process that is consistent with this law.
    • The emission spectrum of the hot gas was found to obey Planck's law.
  • A consequence of Planck's law: A result or phenomenon that stems from this law.
    • The existence of a photon is a direct consequence of Planck's law.
planck's law

A scientist explains Planck's law using a diagram of energy quanta.

Noun
  1. (physics) the basis of quantum theory; the energy of electromagnetic waves is contained in indivisible quanta that have to be radiated or absorbed as a whole; the magnitude is proportional to frequency where the constant of proportionality is given by Planck's constant

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