"Radiation intensity" redirects here. For ionizing radiation, see Radiation flux. For other measures of electromagnetic radiation, see Light intensity (disambiguation).
In radiometry, radiant intensity is the radiant flux emitted, reflected, transmitted or received, per unit solid angle, and spectral intensity is the radiant intensity per unit frequency or wavelength, depending on whether the spectrum is taken as a function of frequency or of wavelength. These are directional quantities. The SI unit of radiant intensity is the watt per steradian (W/sr), while that of spectral intensity in frequency is the watt per steradian per hertz (W·sr−1·Hz−1) and that of spectral intensity in wavelength is the watt per steradian per metre (W·sr−1·m−1)—commonly the watt per steradian per nanometre (W·sr−1·nm−1). Radiant intensity is distinct from irradiance and radiant exitance, which are often called intensity in branches of physics other than radiometry. In radio-frequency engineering, radiant intensity is sometimes called radiation intensity.
radiometry, radiantintensity is the radiant flux emitted, reflected, transmitted or received, per unit solid angle, and spectral intensity is the radiant intensity...
yellow-green light at 555 nm. Light with the same radiantintensity at other wavelengths has a lower luminous intensity. The curve which represents the response...
radiometry, radiant energy is the energy of electromagnetic and gravitational radiation. As energy, its SI unit is the joule (J). The quantity of radiant energy...
Irradiance is often called intensity, but this term is avoided in radiometry where such usage leads to confusion with radiantintensity. In astrophysics, irradiance...
radiometry, but in radiometry this usage leads to confusion with radiantintensity. Radiant exitance of a surface, denoted Me ("e" for "energetic", to avoid...
are commonly known as intensity: Radiantintensity, a radiometric quantity measured in watts per steradian (W/sr) Luminous intensity, a photometric quantity...
In radiometry, radiance is the radiant flux emitted, reflected, transmitted or received by a given surface, per unit solid angle per unit projected area...
by a light source in a particular direction. Luminous intensity is analogous to radiantintensity, but instead of simply adding up the contributions of...
In radiometry, radiant flux or radiant power is the radiant energy emitted, reflected, transmitted, or received per unit time, and spectral flux or spectral...
regardless of the observer's angle of view. More precisely, the reflected radiantintensity obeys Lambert's cosine law, which makes the reflected radiance the...
the apparent temperature difference at the sensor and the contrast radiantintensity (CRI) definitions. The apparent temperature difference method of defining...
transfer), radiant heat flux per unit area per unit solid angle (W·m−2·sr−1) Electric current, whose value is sometimes called current intensity in older...
Alternative symbols sometimes seen: W or E for radiant energy, P or F for radiant flux, I for irradiance, W for radiant exitance. Spectral quantities given per...
radiometry, radiant energy density is the radiant energy per unit volume. The SI unit of radiant energy density is the joule per cubic metre (J/m3). Radiant energy...
so the symbol "sr" is used to indicate a solid angle. For example, radiantintensity can be measured in watts per steradian (W⋅sr−1). The steradian was...
called irradiance. Flux emitted from a surface may be called radiant exitance or radiant emittance. The ratio of irradiance reflected to the irradiance...
Alternative symbols sometimes seen: W or E for radiant energy, P or F for radiant flux, I for irradiance, W for radiant exitance. Spectral quantities given per...
In radiometry, radiant exposure or fluence is the radiant energy received by a surface per unit area, or equivalently the irradiance of a surface, integrated...
temperature), mole (mol, amount of substance), and candela (cd, luminous intensity). The system can accommodate coherent units for an unlimited number of...
three base units (for temperature, amount of substance, and luminous intensity) were added later. The early metric systems defined a unit of weight as...
radiation per unit solid angle per emitting source area W/(m2⋅sr) M T−3 Radiantintensity I Power of emitted electromagnetic radiation per unit solid angle...
full width at half maximum and the radiation angle at half maximum radiantintensity. Effective mode volume is proportional to the breadth of the relative...
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