Intensity may refer to:

In colloquial use

Amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of a ...

Level (disambiguation) Level or levels may refer to: Engineering * Level (instrument), a device used to measure true horizontal or relative heights * Spirit level, an instrument designed to indicate whether a surface is horizontal or vertical * Canal pound or level * ...

Magnitude (disambiguation) Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

In physical sciences

Physics

Intensity (physics) In physics, the intensity or flux of radiant energy is the power transferred per unit area, where the area is measured on the plane perpendicular to the direction of propagation of the energy. In the SI system, it has units watts per square me ...

, power per unit area (W/m²) * Field strength of electric, magnetic, or electromagnetic fields (V/m, T, etc.) *

Intensity (heat transfer) In the field of heat transfer, intensity of radiation I is a measure of the distribution of radiant heat flux per unit area and solid angle, in a particular direction, defined according to :dq = I\, d\omega\, \cos \theta\, dA where *dA is the in ...

, radiant heat flux per unit area per unit solid angle (W·m⁻²·sr⁻¹) *

Electric current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The movin ...

, whose value is sometimes called ''current intensity'' in older books

Optics

Radiant intensity 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 take ...

, power per unit solid angle (W/sr) *

Luminous intensity In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human ...

, luminous flux per unit solid angle (lm/sr or cd) * Irradiance, power per unit area (W/m²)

Astronomy

* Radiance, power per unit solid angle per unit projected source area (W·sr⁻¹·m⁻²)

Seismology

* Mercalli intensity scale, a measure of earthquake impact *

Japan Meteorological Agency seismic intensity scale The Japan Meteorological Agency (JMA) Seismic Intensity Scale (known in Japan as the Shindo seismic scale) is a seismic intensity scale used in Japan to categorize the intensity of local ground shaking caused by earthquakes. The JMA intensi ...

, a measure of earthquake impact *

Peak ground acceleration Peak ground acceleration (PGA) is equal to the maximum ground acceleration that occurred during earthquake shaking at a location. PGA is equal to the amplitude of the largest absolute acceleration recorded on an accelerogram at a site during a part ...

, a measure of earthquake acceleration (g or m/s²)

Acoustics

* Sound intensity, sound power per unit area

Other uses

* Value intensity in philosophy and ethics *In video luminous emittance, the luminous flux per unit area (lm/m² or lux) *

Energy intensity Energy intensity is a measure of the energy inefficiency of an economy. It is calculated as units of energy per unit of GDP. * High energy intensities indicate a high price or cost of converting energy into GDP. * Low energy intensity indicat ...

, an economic measure of energy consumed per unit of GDP (J/$, etc.) * Carbon intensity, any of several measures of release of carbon into the environment *

Floor area ratio Floor area ratio (FAR) is the ratio of a building's total floor area (gross floor area) to the size of the piece of land upon which it is built. It is often used as one of the regulations in city planning along with the building-to-land ratio. The ...

, the ratio of the total floor area of buildings on a certain location to the size of the land of that location, or the zoning limit imposed on such a ratio * Intensity (measure theory), the average value a measure assigns to an interval of length one * Exercise intensity, a measure of how much work is done during exercise (% of max heart rate) * ''Intensity'' (novel), a 1995 novel by Dean Koontz ** ''Intensity'' (film), a 1997 made-for-TV movie based on the novel * ''Intensity'' (Charles Earland album), 1972 * ''Intensity'' (Art Pepper album), 1960 * ''Intensity'' (John Klemmer album), 1973 *'' Intensity!'', a 1999 album by The Bambi Molesters * ''Intensity'' (video game), a 1988 video game. *"Intensity", a song by Linda Perhacs from the album '' The Soul of All Natural Things''