intensities

Intensities is the plural form of intensity, a term used across disciplines to describe the strength, magnitude, or rate of a quantity in a given region or period. While the precise meaning varies by context, intensity generally conveys how strong or concentrated a phenomenon is.

In physics and engineering, intensity commonly means power per unit area. For a radiant, acoustic, or other wave, intensity I equals the time-averaged power P passing through a unit area A, I = P/A, with units of watts per square meter (W/m^2). For electromagnetic waves, intensity relates to the Poynting vector’s magnitude. Luminous intensity, measured in candela (cd), is a photometric quantity representing radiant intensity per unit solid angle, adjusted for human eye sensitivity; it is distinct from radiant irradiance, which is power per unit area in watts per square meter. In optics and radiometry, several related quantities—radiant intensity, irradiance, radiance, and luminance—describe different aspects of light’s distribution.

In statistics and probability, intensity describes the rate at which events occur in time or space. The intensity function (or rate) of a point process gives the expected number of events per unit time or area and is central to modeling arrivals and spatial patterns. In everyday language, intensity also denotes the strength of a stimulus or experience—how strong, vivid, or forceful it feels. In music and visual arts, intensity commonly refers to the dynamic level or expressive force conveyed.