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newton meter squared per kilogram squared (N⋅m 2 /kg 2) shear modulus: pascal (Pa) or newton per square meter (N/m 2) acceleration due to gravity: meters per second squared (m/s 2), or equivalently, newtons per kilogram (N/kg) magnetic field strength: ampere per meter (A/m) Hamiltonian: joule (J)
watt per square metre per hertz W⋅m −2 ⋅Hz −1: M⋅T −2: Radiant exitance of a surface per unit frequency or wavelength. The latter is commonly measured in W⋅m −2 ⋅nm −1. "Spectral emittance" is an old term for this quantity. This is sometimes also confusingly called "spectral intensity". M e,λ [nb 4] watt per square metre ...
Characteristic X-rays are emitted when outer-shell electrons fill a vacancy in the inner shell of an atom, releasing X-rays in a pattern that is "characteristic" to each element. Characteristic X-rays were discovered by Charles Glover Barkla in 1909, [ 1 ] who later won the Nobel Prize in Physics for his discovery in 1917.
Orbital Parameters of a Cosmic Object: . α - RA, right ascension, if the Greek letter does not appear, á letter will appear. δ - Dec, declination, if the Greek letter does not appear, ä letter will appear.
The millimetre (SI symbol: mm) is a unit of length in the metric system equal to 10 −3 metres ( 1 / 1 000 m = 0.001 m). To help compare different orders of magnitude, this section lists lengths between 10 −3 m and 10 −2 m (1 mm and 1 cm). 1.0 mm – 1/1,000 of a meter; 1.0 mm – 0.03937 inches or 5/127 (exactly)
X-rays are also emitted by stellar corona and are strongly emitted by some types of nebulae. However, X-ray telescopes must be placed outside the Earth's atmosphere to see astronomical X-rays, since the great depth of the atmosphere of Earth is opaque to X-rays (with areal density of 1000 g/cm 2), equivalent to 10 meters thickness of water. [16]
The x unit (symbol xu) is a unit of length approximately equal to 0.1 pm (10 −13 m). [1] It is used to quote the wavelength of X-rays and gamma rays . Originally defined by the Swedish physicist Manne Siegbahn (1886–1978) in 1925, the x unit could not at that time be measured directly; the definition was instead made in terms of the spacing ...
The International System of Units, internationally known by the abbreviation SI (from French Système international d'unités), is the modern form of the metric system and the world's most widely used system of measurement. It is the only system of measurement with official status in nearly every country in the world, employed in science ...