opacity

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opacity

1. the state or quality of being opaque
2. an opaque object or substance
3. Physics Photog the ratio of the intensity of light incident on a medium, such as a photographic film, to that transmitted through the medium
4. Logic Philosophy the property of being an opaque context

opacity

(oh-pass -ă-tee) A measure of the ability of a gaseous, solid, or liquid body to absorb radiation. It is the ratio of the total radiant energy received by the body to the total energy transmitted through it. For gaseous material of a particular chemical composition, opacity depends on both temperature and density. Various processes contribute to the opacity: energy absorption by electrons bound to an atom or ion, allowing them to jump to a higher level or to escape from the atom as free electrons (bound-bound or bound-free absorption); absorption by free electrons (free-free absorption); scattering of photone of radiation by free electrons or atoms (Compton scattering); absorption of γ-ray photons by ambient ‘gas' photons (photon-photon absorption). The negative hydrogen ion, H, is a particularly important source of opacity in a star like the Sun, and the solar opacity is seen to drop rapidly to zero at the Sun's limb.

Opacity

Quality of being impenetrable by light; not reflecting light, or transmitting light, neither transparent nor translucent.

opacity

[ō′pas·əd·ē]
(optics)
The light flux incident upon a medium divided by the light flux transmitted by it.

opacity

The quality of being opaque, as the capacity of a paint to cover or obliterate a background over which it is applied.

opacity

Being "opaque," which prevents light from shining through. For example, in an image editing program, the opacity level for some function might range from completely transparent (0) to completely opaque (100).
References in periodicals archive ?
Radiative opacities for carbon- and oxygen-rich mixtures.
New solar opacities, abundances, helioseismology, and neutrino fluxes.
Patients with cortical opacities can also report monocular diplopia and this should always be considered in an older patient with symptoms of diplopia.
Capsular remnants are best seen using retro-illumination from the fundus, where the opacities appear black against the red fundal glow.
18 ppm) and prevalence of diffuse opacities in the permanent first molars and incisors among children is low as well (0.
For comparison of the severity of MIH between the genders and age groups, the three groups of MIH lesions (opacities, enamel breakdown and atypical restorations) were recoded into two severity levels: opacities and disintegration defects.
8%) had only demarcated opacities, but no breakdown or atypical restorations.
Distribution of opacities and disintegration defects among the children with a different number of affected teeth and divided between genders is presented in the Table 3.
The most common abnormalities detected on radiography include reticular opacities, perihilar fibrosis, pleural thickening, and peribronchovascular opacities (6, 7).