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Ionizing radiation energy absorbed per unit mass gray (Gy = J/kg) L 2 T −2: Radiance: L: Power of emitted electromagnetic radiation per unit solid angle per emitting source area W/(m 2 ⋅sr) M T −3: Radiant intensity: I: Power of emitted electromagnetic radiation per unit solid angle W/sr L 2 M T −3: scalar Reaction rate: r: Rate of a ...
In physics and chemistry, it is common to measure energy on the atomic scale in the non-SI, but convenient, units electronvolts (eV). 1 eV is equivalent to the kinetic energy acquired by an electron in passing through a potential difference of 1 volt in a vacuum. It is common to use the SI magnitude prefixes (e.g. milli-, mega- etc) with ...
For ionising radiation, the gray is the SI unit of specific energy absorbed by matter known as absorbed dose, from which the SI unit the sievert is calculated for the stochastic health effect on tissues, known as dose equivalent.
The rad is a unit of absorbed radiation dose, defined as 1 rad = 0.01 Gy = 0.01 J/kg. [1] It was originally defined in CGS units in 1953 as the dose causing 100 ergs of energy to be absorbed by one gram of matter. The material absorbing the radiation can be human tissue, air, water, or any other substance.
The process is described by the Einstein coefficient (m 3 J −1 s −2), which gives the probability per unit time per unit energy density of the radiation field per unit frequency that an electron in state 1 with energy will absorb a photon with an energy E 2 − E 1 = hν and jump to state 2 with energy .
Examples of large transformations between rest energy (of matter) and other forms of energy (e.g., kinetic energy into particles with rest mass) are found in nuclear physics and particle physics. Often, however, the complete conversion of matter (such as atoms) to non-matter (such as photons) is forbidden by conservation laws.
The joule (/ dʒ uː l / JOOL, or / dʒ aʊ l / JOWL; symbol: J) is the unit of energy in the International System of Units (SI). [1] In terms of SI base units, one joule corresponds to one kilogram-square metre per square second (1 J = 1 kg⋅m 2 ⋅s −2).
Matter that does not absorb all incident radiation emits less total energy than a black body. Emissions are reduced by a factor ε {\displaystyle \varepsilon } , where the emissivity , ε {\displaystyle \varepsilon } , is a material property which, for most matter, satisfies 0 ≤ ε ≤ 1 {\displaystyle 0\leq \varepsilon \leq 1} .