Halflife

= Half Life = Is defined as the time required for half of any initial quantity of something to decay. Commonly used in radioactive decay but also used in pharmacological decay. T he half-life is defined in terms of probablitlity based on the number of disintegrations per second of a material to decrease by one-half. In terms of radioactive material alpha and beta are generally slower at decay than gamma. Some radiological decay or half lifes are listed below: = History of Half Life = The original term, dating to 1907, was "half-life period", which was later shortened to "half-life" in the early 1950s. The name was originally used to describe a characteristic of unstable atoms radioactive decay, but it may apply to any quantity which follows a set-rate decay. = Application of Half Life = The decay of many physical quantities is not exponential—for example, the evaporation of water from a puddle, or (often) the chemical reaction of a molecule. In such cases, the half-life is defined the same way as before: as the time elapsed before half of the original quantity has decayed. However, unlike in an exponential decay, the half-life depends on the initial quantity, and the prospective half-life will change over time as the quantity decays.

The decay of many physical quantities is not exponential—for example, the evaporation of water from a puddle, or (often) the chemical reaction of a molecule. In such cases, the half-life is defined the same way as before: as the time elapsed before half of the original quantity has decayed. However, unlike in an exponential decay, the half-life depends on the initial quantity, and the prospective half-life will change over time as the quantity decays.

R eferences
 * 1) Beiser, A. (1988). //Physical Science (2nd Edition) //. New York, NY: McGraw Hill
 * 2) Half-life. (2012, February 29). In //Wikipedia, The Free Encyclopedia//. Retrieved 14:54, March 1, 2012, from []
 * 3) half-life. In (2010). //Volume 5// (15 ed. p. 633). Chicago: Encyclopaedia Britannica, Inc.

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