﻿ Half life equation

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12/23/2014
08:18 | Author: Emma Coleman Half-life - Wikipedia, the free encyclopedia

see Half-Life (series). For the first video game in the series, see Half-Life (video game). It is a characteristic unit for the exponential decay equation. The term.

For three or more processes, the analogous formula is:

A half-life usually describes the decay of discrete entities, such as radioactive atoms. In that case, it does not work to use the definition "half-life is the time required for exactly half of the entities to decay". For example, if there are 3 radioactive atoms with a half-life of one second, there will not be "1.5 atoms" left after one second.

The three parameters, , and are all directly related in the following way:

For example, the image on the right is a simulation of many identical atoms undergoing radioactive decay.

Comments (1)Read more ## Radioactive Decay and Decibel Levels - Cool Math

10/22/2014
06:24 | Author: Lauren Ross Radioactive Decay and Decibel Levels - Cool Math

Plutonium-239 has a half-life of 24,110 years. "Half-life means that, if you have 100 pounds of Plutonium-239 In 24,110 years, you'd still have 50 pounds left.

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Hey, did you know that YOU are radioactive? You've got this stuff in you called Carbon-14... It comes from cosmic rays that rain down on the earth (and us) from outer space. (By the way, you are mostly Carbon-12, which is not radioactive. That's why we are called "Carbon-based life forms." Man, I've really watched too much Star Trek.).

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If we mess with this a bit, we can make it simpler:

Continued on the next page.

Scientists use Carbon-14 to make a guess at how old some things are -- things that used to be alive like people, animals, wood and natural cloths.

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## Half Life Calculator

8/21/2014
04:14 | Author: Emma Coleman Half Life Calculator

Free online tool to calculate any one of the values from the other three in a half-life formula as well as to convert between half life, mean lifetime, and decay.

where N 0 is the initial quantity N t is the quantity that still remains after a time t, t 1/2 is the half-life τ is the mean lifetime λ is the decay constant.

N t = N 0 (1/2)t/t 1/2 N t = N 0 e-t/τ N t = N 0 e-λt.

By definition, half-life is the period of time it takes for a substance undergoing decay to decrease by half. An exponential decay process can be described by any of the following three equivalent formulas:

Please provide anyone of the following to get the other two.

The following tools can generate any one of the values from the other three in the half-life formula for a substance undergoing decay to decrease by half.

Please provide any three of the following to calculate the fourth value.

t 1/2 = ln(2)τ = ln(2)/λ

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## Half Lives

6/20/2014
02:32 | Author: David Perry Half Lives

For a zero order reaction A Arrow products , rate = k: t½ = [Ao] / 2k. For a first order reaction A Arrow products.

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## Radioactive Half-Life - HyperPhysics

4/19/2014
12:30 | Author: David Perry Radioactive Half-Life - HyperPhysics

The radioactive half-life for a given radioisotope is a measure of the tendency of the nucleus to "decay" or so the standard form of the decay equation is:.

The radioactive half-life for a given radioisotope is a measure of the tendency of the nucleus to "decay" or "disintegrate" and as such is based purely upon that probability. The tiny nuclear size compared to the atom and the enormity of the forces which act within it make it almost totally impervious to the outside world. The half-life is independent of the physical state (solid, liquid, gas), temperature, pressure, the chemical compound in which the nucleus finds itself, and essentially any other outside influence.

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