Definition OF radioactivity||Activity OF a sample||Laws OF radioactivity||Half life||Mean life||Examples on radioactivity

In a mean life of a radioactive sample

Radioactivity||Mean Life|| Half Life

Half-life period for radioactive element is

Half life period and mean life period of a radioactive element are

At t=0 , number of radioactive nuclei of a radioactive substance are x and its radioactivity is y. Half-life of radioactive substance is T. Then,

How many atoms decay in one mean life time of a radioactive sample-