Radiant energy

Radiant energy and electromagnetic radiation are two terms that refer to the same concept. Radiant energy travels through space in the form of waves. These waves consist of oscillating electric and magnetic fields.

  • Electromagnetic radiation can be viewed as either electromagnetic waves or a stream of photons. These two perspectives are not mutually exclusive but rather complementary, as explained by the concept of wave-particle duality.
    • In the wave perspective, electromagnetic radiation is characterized by oscillating electric and magnetic fields that propagate through space. The energy of the radiation is distributed throughout the wave, and its intensity depends on the wave’s amplitude and frequency.
    • In the photon perspective, electromagnetic radiation is described as a stream of massless particles called photons. Each photon carries a discrete amount of energy, known as the photon energy, which is directly proportional to the radiation’s frequency.The wave-particle duality concept, deeply rooted in quantum field theory, reconciles these two seemingly contradictory perspectives. It explains that electromagnetic radiation exhibits both wave-like and particle-like properties depending on the experimental setup or observation method.
  • Radiant energy includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays. Each type of radiation is characterized by its distinct wavelength and frequency range.
  • The quantity of radiant energy is typically measured in terms of radiant flux over time. Radiant flux represents the amount of radiant energy passing through a unit area per unit time. It is commonly expressed in units of watts per square meter (W/m²).
About light, radiation, radiant energy & electromagnetic energy

There is a difference in meaning between the terms light, electromagnetic radiation, radiant energy and electromagnetic energy in physics.

    • Light is best used to refer to the subset of electromagnetic radiation that is visible to the human eye, ranging from violet (shorter wavelengths) to red (longer wavelengths).
Electromagnetic radiation
    • Electromagnetic radiation refers to the transfer of all forms of electromagnetic radiation through space by electromagnetic waves and includes gamma rays, ultraviolet (UV), infrared (IR), X-rays, and radio waves, as well as visible light.
Radiant energy
    • Radiant energy is most commonly used to refer to electromagnetic radiation carried by electromagnetic waves. Radiant energy can be measured using instruments such as photometers, which detect the intensity of light or other forms of electromagnetic radiation.
Electromagnetic energy
  • Electromagnetic energy is a more general term that refers to any form of energy that is carried by electromagnetic waves, including both radiant energy and other types of energy that are not radiant (e.g., static electric fields).
  • The type of energy associated with electromagnetic radiation is a measurable quantity in physics, and its measurement is essential for understanding and analyzing physical systems and processes.
  • The unit of measurement for electromagnetic energy in the International System of Units (SI) is the joule (J), which is defined as the amount of energy required to perform one joule of work
  • The electronvolt (eV) is another unit of energy commonly used in atomic and subatomic physics.