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Radiant energy

Radiant energy is energy that is transported by waves. This includes energy transception in the form of waves through space or various media. Radiant energy is also energy transfered through electromagnetic waves. Solar Energy is a type of radiant energy. Radiant energy may be calculated by integrating radiant power with respect to time. Radiant energy is usually expressed in joules.

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Analysis

Radiant energy refers to the energy of electromagnetic radiation. Because EM radiation can be seen as photon-based, radiant energy can be viewed as the energy carried by the relevant photons. Radiating bodies have typical portions of the electromagnetic spectrum in which their radiation is concentrated. Such radiating bands may be sharply defined, such as is seen in star spectra, or may be more diffused.

EM radiation has three principal components: wavelength and frequency, which are strictly inversely proportional, and intensity, which determines the amount of energy carried by the radiation. Radiant energy may be originated in a body or reflected from another body (in which case it may be refracted or otherwise modified).

Open systems

Open systems are sometimes referred to as "radiant energy" systems because of the circuit (a phantom loop) that includes the environment. In geophysics, transparent greenhouse gases trap the sun's radiant energy (at certain wavelengths), allowing them to penetrate deep into the atmosphere or all the way to the Earth's surface, where they are re-emitted as longer wavelength radiation (chiefly infrared radiation). Radiant energy produced in the sun is a result of nuclear fusion and some of it, ultimately, interacts with the earth's atmosphere and surface.

Applications and patents

Radiant energy, as distinguished from convective and conductive energy, is used for heating homes. One of the earliest wireless telephones was based on radiant energy. The device had its resonance tuned to a particular frequency of other repeaters to communicate between each. According to Nikola Tesla, it was the "... [S]implest ways [to detect the radiant energy ...] the low frequency gave audible notes. [... in a field, there was] placed a conductor, a wire or a coil, and then [Tesla] would get a note [...] characteristics of the audible note".

The United States Patent Offices has a classification of radiant energy for patent applications (Class 250, a residual class for methods and apparatus involving radiant energy). This class provides for all methods and apparatus for using, generating, controlling or detecting radiant energy, combinations including such methods or apparatus, subcombinations of same and accessories therefore not classifiable elsewhere by the patent office. [1]

SI radiometry units

SI radiometry units

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Quantity SI unit Symbol Notes
radiant energy joule J energy
radiant flux watt W radiant energy per unit time, also called radiant power
radiant intensity watts per steradian W·sr-1 power per unit solid angle
radiance watts per steradian per square metre W·sr-1·m-2 power per unit solid angle per unit area
irradiance watts per square metre W·m-2 power per unit area, also called radiant emittance or radiant exitance
spectral radiance watt per steradian per cubic metre W·sr-1·m-3 commonly measured in W·sr-1·m-2·nm-1
spectral irradiance watt per cubic metre W·m-3 commonly measured in W·m-2·nm-1

See also

Radio spectrum
ELF | SLF | ULF/VF | VLF | LF/LW | MF/MW | HF/SW | VHF | UHF | SHF | EHF
3 Hz | 30 Hz | 300 Hz | 3 kHz | 30 kHz | 300 kHz | 3 MHz | 30 MHz | 300 MHz | 3 GHz | 30 GHz | 300 GHz


Electromagnetic Spectrum

Radio waves | Microwave | Infrared | Optical spectrum | Ultraviolet | X-ray | Gamma ray


Visible: Red | Orange | Yellow | Green | Blue | Indigo | Violet

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