An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

فرهنگ ریشه شناختی اخترشناسی-اخترفیزیک

M. Heydari-Malayeri    -    Paris Observatory

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Number of Results: 304 Search : act
weight fraction
  برخه‌ی ِ وزنی   
barxe-ye vazni

Fr.: fraction en poids   

Same as → weight concentration.

weight; → fraction.

weight-fraction concentration
  برخه‌ی ِ وزنی ِ دبزش   
barxe-ye vazni-ye dabzeš

Fr.: concentration en poids   

Same as → weight concentration.

weight; → fraction; → concentration.

X-ray diffraction
  پراش ِ پرتو ِ ایکس   
parâš-e partow-e iks

Fr.: diffraction de rayons X   

The diffraction of X-rays by the atoms or ions of a crystal. The wavelength of X-rays are comparable to the size of interatomic spacings in solids. Since the atoms in a crystal are arranged in a set of regular planes, crystals serve as three-dimensional diffraction gratings for X-rays. Planes of repetition within the atomic structure of the mineral diffract the X-rays. The pattern of diffraction thus obtained is therefore used to identify minerals by bombarding them with X-rays.

X-ray; → diffraction.

Yerkes refractor
  شکست‌گر ِ یرکیز   
šekastgar-e Yerkes

Fr.: réfracteur de Yerkes   

The largest → refracting telescope and the last of the great refractors with a lens diameter of 102 cm (f/d = 19), completed in 1897. The lens was ground by American telescope builders Alvan Clark & Sons. Used mainly for both visual and photographic studies of double stars, it is typical of the long-tube refractors traditionally employed in such work.

After Yerkes Observatory; → refractor.

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