Question

Find the decay constant and the mean lifetime of `Co^(55)` radionuclide if its activity is known to decrease`4.0%` per hour. The decay product is nonradioactive.

Answer 1

If the decay constant (in `("hour")^(-1)`) is `lambda`, then the activity after one hour will decrease by a factor `e^(-lambda)`. Hence
`0.96= e^(-lambda)`
or `lambda= 1.11xx10^(-5)s^(-1)= 0.0408 per hour`
The mean life time is `24.5 hour`