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Encyclopedia > Röntgen

In SI (disambiguation). The International System of Units (abbreviated SI from the French phrase, Système International dUnités) is the most widely used system of units. It is used for everyday commerce in virtually every country of the world except the United States, Liberia and Myanmar, and... SI units, 1 R = 2.58×10-4 The coulomb, symbol C, is the SI unit of electric charge, and is defined in terms of the ampere: 1 coulomb is the amount of electric charge (quantity of electricity) carried by a current of 1 ampere flowing for 1 second. It is also about 6.241506×1018 times the... C/ The international prototype, made of platinum-iridium, which is kept at the BIPM under conditions specified by the 1st CGPM in 1889. The kilogram (symbol: kg) is the SI base unit of mass. A gram is defined as one thousandth of a kilogram. Conversion of units describes equivalent units of... kg.

Natural background exposure is around 10 Micro is a SI prefix in the SI system of units denoting a factor of 10−6 (one millionth). The symbol for it is the micro sign (µ). Confirmed in 1960, the prefix comes from the Greek μικρός (transliterated: mikros), meaning small. More generally, the... μR per hour. A dose of 500 R in 5 The hour was originally defined in Egypt as 1/24 of a day, based on their duo-decimal numbering system (which counted finger joints on each hand). In modern usage, an hour was redefined as a unit of time 60 minutes, or 3600 seconds in length. It is approximately 1... h is lethal for humans.

The röntgen is an obsolete unit, superseded by the A gray, (symbol: Gy), is the SI unit of energy for the absorbed dose of radiation. One gray is the absorption of one joule of radiation energy by one kilogram of matter. One gray equals 100 rad, an older unit . It was defined in 1940 by Louis Harold Gray (1905... gray. In dry air, 1 Gy is approximately equal to 100 röntgens.

The röntgen was occasionally used to measure exposure to radiation in other forms than X-rays or gamma rays. To adjust for the different impact of different forms of radiation on biological matter, the "Röntgen equivalent man" or rem was also in use. Exposure in rems is equal to the exposure in röntgens multiplied by the Q value, a constant describing the type of radiation. The rem is now superseded by the The sievert (symbol Sv) is an SI derived unit of equivalent dose or effective dose (of radiation), and so is dependent upon the biological effects of radiation as opposed to the physical aspects, characterised by the absorbed dose (measured in grays). The equivalent dose to a tissue is found by... sievert (see the latter for a list of Q values).

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