### About

### Translations

Code | Language | Translator | Run | |
---|---|---|---|---|

### Software Requirements

Android | iOS | Windows | MacOS | |

with best with | Chrome | Chrome | Chrome | Chrome |

support full-screen? | Yes. Chrome/Opera No. Firefox/ Samsung Internet | Not yet | Yes | Yes |

cannot work on | some mobile browser that don't understand JavaScript such as..... | cannot work on Internet Explorer 9 and below |

### Credits

Fu-Kwun Hwang - Dept. of Physics, National Taiwan Normal Univ.; lookang

### end faq

### Theory

The law of radioactive decay predicts how the number of the not decayed nuclei of a given radioactive substance decreases in the course of time. The GREY circles of this simulation symbolize 100 (variable selectable up 400 or 1024) to atomic nuclei of a radioactive substance whose half-life period (T_{1/2)} amounts to 0.1 to 3.0 seconds. The scientfic graph on the right, in number of radioactive atoms versus time, RED trail represents represents the Number of radioactive atoms, Nā not yet decayed nuclei at a given time t, predicted by the following law:

N_{1} = N_{0} e -(ln2/T_{1/2})) t

when you play with the show model option, show me N_{1}= N_{o}*exp(-ln(2)/T_{1/2}*t)

similarly it is possible to also predict the number of decayed atoms using the formula

N_{2} = N_{0} -N_{0} e -(ln2/T_{1/2})) t

when you play with the show model option, show me N2 = No-No*exp(-ln(2)/T_{1/2}*t)

in the option both2 when selected, can display the rate of radioactive atoms versus time,

dN = pN0 e -(ln2/T_{1/2)}) t

when you play with the show model option, show me dN = p*N0*exp(-ln(2)/T_{1/2}*t)

the terms use are

N1 .... number of the not decayed nuclei

N_{2} .... number of the decayed nuclei

N_{0} ... number of the initially existing nuclei at time, t = 0

t .... time

T_{1/2} .... is the time taken for the activity of a given amount of a radioactive substance to decay to half of its initial value

λ, or sometimes also known as "lambda" the inverse of the mean lifetime, sometimes referred to as simply decay rate.

p is probability of decaying where 0 means no chance at all, 1 is 100% chance of decaying

Formula that related some of these terms are

T_{1/2} = ln(2)/λ

\( \lambda = \frac{p}{dt} \)

The Ordinary Differential equations used is

\( \frac{dN_{1}}{dt} = - \lambda_{1}N_{1} \)

### Versions

- http://weelookang.blogspot.sg/2016/02/a-comparison-of-2-javascript-nuclear.html comparison of 2 HTML5 versions
- http://weelookang.blogspot.sg/2015/12/ejss-radioactive-decay-model.html lookang's blogpost about this JavaScript version
- http://www.phy.ntnu.edu.tw/ntnujava/index.php?topic=194.0 by Fu-Kwun Hwang original Java version
- http://www.opensourcephysics.org/items/detail.cfm?ID=10576 by Wolfgang Christian similar Java version

### Other Resources

- http://www.opensourcephysics.org/items/detail.cfm?ID=13978&S=7 Two-State Nuclear Decay JS Model written by Wolfgang Christian
- http://www.walter-fendt.de/html5/phen/lawdecay_en.htm by Walter fendt

### end faq

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