Half-Life
See: Rate, Attrition Rate, Decay Function.
References
2013
- http://en.wikipedia.org/wiki/Half-life
- Half-life (t½) is the time required for a quantity to fall to half its value as measured at the beginning of the time period. In physics, it is typically used to describe a property of radioactive decay, but may be used to describe any quantity which follows an exponential decay.
>> The original term, dating to Ernest Rutherford's discovery of the principle in 1907, was "half-life period", which was shortened to "half-life" in the early 1950s.[1]
Half-life is used to describe a quantity undergoing exponential decay, and is constant over the lifetime of the decaying quantity. It is a characteristic unit for the exponential decay equation. The term "half-life" may generically be used to refer to any period of time in which a quantity falls by half, even if the decay is not exponential. For a general introduction and description of exponential decay, see exponential decay. For a general introduction and description of non-exponential decay, see rate law.
The converse of half-life is doubling time.
The table on the right shows the reduction of a quantity in terms of the number of half-lives elapsed.
- Half-life (t½) is the time required for a quantity to fall to half its value as measured at the beginning of the time period. In physics, it is typically used to describe a property of radioactive decay, but may be used to describe any quantity which follows an exponential decay.
- ↑ John Ayto, "20th Century Words" (1989), Cambridge University Press.