exposure time


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exposure time

[ik′spō·zhər ‚tīm]
(civil engineering)
The time period of interest for seismic hazard calculations such as the design lifetime of a building or the time over which the numbers of casualties should be estimated.
(physics)
The amount of time a material is illuminated or irradiated.

Exposure Time

 

the time interval t during which light-sensitive photographic material is exposed to the continuous action of light. If the radiation power (intensity of illumination on the emulsion layer) is varied during the time of exposure, a distinction is then made between the full exposure time tf and the effective exposure time te, which is less than tf. The effective exposure time is the interval of time during which the photographic layer would be exposed to the same amount of light as during the full exposure time if the radiation power were to remain constant and equal to its maximum value. If the variation of the exposure on the film layer is associated with the type of shutter used in cameras (for example, a diaphragm shutter whose blades are located in or near the pupil of the lens), the ratio of te to tf is called the shutter efficiency. The shutter efficiency is higher with a longer exposure and a smaller lens aperture ratio. The product of the exposure time and the intensity of illumination L is called the exposure or the amount of illumination H = Lt. The same exposure can produce a slightly different photographic effect depending on the relationship between L and t; a similar photochemical phenomenon is called the phenomenon of noninterchangeability.

IU. N. GOROKHOVSKII

exposure time

The time during which a light-sensitive material is subjected to the action of light.
References in periodicals archive ?
After 73 days of exposure time, an increased current in the intensity of the absorption band was observed at approximately 1720 cm-1, which can be assigned to the C=O stretch of the saturated aliphatic carbonyl group.
According to the Guide Note, exposure time matters to the valuation process because:
The thesis of this article is that exposure time can only be (1) a historical fact as experienced by a property that has been sold, or (2) a standard that is explicitly or implicitly defined in every value definition.
The dependence of the thickness of removed polymer layer on the plasma exposure time is shown in Fig.
In the present study, although the effect of hypertonic saline on protoscolices was more than hypertonic glucose in lower exposure times, but the effect of both 20% hypertonic saline and 40% hypertonic glucose was 100% after 20 min exposure time.
Adherence studies are particularly vulnerable to unobservable exposure time bias.
Effect of exposure time and ratio of hosts to female parasitoids on offspring production of Diachasmimorpha longicaudata (Hymneoptera: Braconidae) reared on Anastrepha fraterculus (Diptera: Tephritidae) larvae.
As seen in Figure 3, the average crater depth versus exposure time plots for PBT are linear regardless of the irradiance level or length of exposure and are dependent only on the level of irradiance (indicating law of reciprocity obeyed).
Unlike the tendency of previous studies, in which the magnetic field range and exposure time used are limited [5, 16], and others in which only one scan is performed with exposure times [15, 16, 17], this study aims at extending the range studied factors, in order to investigate the possible trend that may have the response curves for the different variables measured and, finding a precise dose for optimal response of plants exposed.
The study provided prospective injury incidence and prevalence data for South African cricketers playing at international level over a two-season period, highlighting the increased injury prevalence for away matches and an increased match injury incidence for test and ODI matches, possibly as a result of increased match exposure time.
A single exposure index was identified for each original study and, where data were available, each combination of exposure time window and pesticide type (unspecified, insecticides, herbicides).