英语词汇“point source”的英英意思、用法、释义、翻译、读音、例句、短语、词组-英语词典

point source

noun

1 Physics A source of energy, such as light or sound, which can be regarded as having negligible dimensions.That is why we often speak of the planetary ‘disk’ in astronomy: even under slight magnification the human eye interprets a planet as a 2 dimensional source of light and not a point source....

Whenever an advancing wavefront of light encounters a barrier in which there is a hole, this hole acts as if it were a point source of light, with radiation of the same wavelength moving beyond the barrier away from the hole.
Illuminance is the measurement of how bright a point source of light appears to the eye.

2A localized and stationary source of pollution. Compare with non-point source.However, in a British study in which the authors compared a population living around a point source of air pollution with a control population, no increase in the prevalence of low birth-weight was evident in the polluted area....

If the pesticide - toxic by definition - got into the stream, didn't the spray nozzle on the helicopter count as a point source of pollution, just like a factory pipe?
The simulation showed that under still and convective conditions the vapours emitted by a point source rapidly form stationary envelopes around the leaves.

单词	point source
释义	point source noun 1 Physics A source of energy, such as light or sound, which can be regarded as having negligible dimensions.That is why we often speak of the planetary ‘disk’ in astronomy: even under slight magnification the human eye interprets a planet as a 2 dimensional source of light and not a point source.... Whenever an advancing wavefront of light encounters a barrier in which there is a hole, this hole acts as if it were a point source of light, with radiation of the same wavelength moving beyond the barrier away from the hole. Illuminance is the measurement of how bright a point source of light appears to the eye. 2A localized and stationary source of pollution. Compare with non-point source.However, in a British study in which the authors compared a population living around a point source of air pollution with a control population, no increase in the prevalence of low birth-weight was evident in the polluted area.... If the pesticide - toxic by definition - got into the stream, didn't the spray nozzle on the helicopter count as a point source of pollution, just like a factory pipe? The simulation showed that under still and convective conditions the vapours emitted by a point source rapidly form stationary envelopes around the leaves.
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