optyka: Attenuation

Evidence: 52 • authority: 72

The linear attenuation coefficient, attenuation coefficient, or narrow-beam attenuation coefficient characterizes how easily a volume of material can be penetrated by a beam of light, sound, particles, or other energy or matter. A coefficient value that is large represents a beam becoming attenuated as it passes through a given medium, while a small value represents that a beam will experience little or no loss in the medium. The (derived) SI unit of attenuation coefficient is the reciprocal metre (m−1). Extinction coefficient is another term for this quantity, often used in meteorology and climatology. The attenuation length is the reciprocal of the attenuation coefficient.

Evidence: 43 • authority: 72

Evidence: 43 • authority: 72

In physics, optical depth or optical thickness is the natural logarithm of the ratio of incident to transmitted radiant power through a material. Thus, the larger the optical depth, the smaller the fraction of transmitted radiant power through the medium. Spectral optical depth or spectral optical thickness is the natural logarithm of the ratio of incident to transmitted spectral radiant power through a material. Optical depth is a dimensionless quantity. Although it is a monotonically increasing function of path length, it is not a physical distance itself, approaching zero as the path length vanishes. The use of the term "optical density" for optical depth is discouraged. In chemistry, a…

Evidence: 43 • authority: 72

In physics, the cross section is a measure related to the probability that a specific process will take place in a collision of two particles. For example, the Rutherford cross section is a measure of probability that an alpha particle will be deflected by a given angle during an interaction with an atomic nucleus. Cross section is typically denoted σ (sigma) and has dimension of area, with units of square meter or more often in barns. In a way, it can be thought of as the size of the object that the excitation must hit in order for the process to occur, but more exactly, it is a parameter of a stochastic process. When two discrete particles interact in classical physics, their mutual cross…

Evidence: — • authority: 62

In physics, attenuation – colloquially, damping – is the gradual loss of flux intensity through a medium. For instance, dark glasses attenuate sunlight, lead attenuates X-rays, and water and air attenuate both light and sound at variable attenuation rates.