# Half life equation

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.

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.

If you believe that your own ed content is on our Site without your permission, please follow the Infringement Notice procedure linked here.

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.).

Thanks for visiting 2014 LLC.

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.

## 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

## 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.

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.