Main Concept

The decay rate of a radioactive substance is characterized by its half-life (${\mathrm{\τ}}_{1\/2}$), a quantity that represents the time taken for a given amount of material to decay into half of its initial value. The amount of radioactive substance $N$ left in a sample at time $t$ is given by

$N\left(t\right)\=N_{t\=0} 2^{-t\/{\mathrm{\τ}}_{1\/2}}$,

which means that radioactive substances with big half-life are spent slower than those with small half-life.

The following graph shows a comparison of decay rates of some of the frequently encountered radioactive substances:

Select the reference isotope Fluorine-18Technetium-99mRadon-222Iodine-125Polonium-210Cobalt-57Cobalt-60Strontium-90Cesium-137Americium-241Radium-226Carbon-14Plutonium-239Uranium-234Uranium-235Uranium-238  

Select the second isotope NoneFluorine-18Technetium-99mRadon-222Iodine-125Polonium-210Cobalt-57Cobalt-60Strontium-90Cesium-137Americium-241Radium-226Carbon-14Plutonium-239Uranium-234Uranium-235Uranium-238 

Select the third isotope NoneFluorine-18Technetium-99mRadon-222Iodine-125Polonium-210Cobalt-57Cobalt-60Strontium-90Cesium-137Americium-241Radium-226Carbon-14Plutonium-239Uranium-234Uranium-235Uranium-238  

Specify the amount of radioactive substance

Select time scale -------yearsdayshoursminutes

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