Закон радиоактивного распада. Период полураспада. Изотопы | Физика 11 класс #49 | Инфоурок

[music] law of radioactive decay half-life isotopes Rutherford established that the activity of the transformation of radioactive substances decreases with time, for example, the activity of radon decreases by half in one minute, the activity of uranium decreases much more slowly for each radioactive substance there is a time interval during which the activity decreases by

half this interval is called the half-life half-life is the time during which half of the initial number of radioactive atoms decays we derive the formula for the law of radioactive decay let us denote the number of radioactive atoms at the initial moment of time novo then by the ini half-life this number will be two times

less, that is, equal to n Well 2 time is equal to the half-life after another such interval of time it is equal to two half-lives N will become equal to the product of N Well de by 2 to the second power, that is, by 4 Therefore, after time T small is equal to the

half-life multiplied by N small N is equal to the ratio well d to the power of N small where N small is equal to the ratio of time to the half-life or N is equal the product of N zero by 2 to the power of mi N small or to the power of minus the ratio of time to

the half-life using this formula you can find the number of undecayed nuclei at any given time the half-life is the main value with which you can determine the rate of radioactive decay the shorter the half-life, the shorter the life of the nuclei, the faster the decay for different substances the half-life has different values ​​from fractions of a second to

billions of years for example the half-life of the radioactive nuclide of the chemical element uranium with atomic number 92 and mass number 238 is 4.5 billion years therefore the activity of uranium remains almost unchanged for several years the half-life of radium is 1600 years that is the decay process is much faster this means the activity of