Saved Bookmarks
| 1. |
The half life of a radioactive substance is 20 minutes. The approximate time interval (t_2 - t_1) between the time t_(2)" when "2/3 of it has decayed and timet_(1)" when "1/3 of it had decayed is : |
|
Answer» 14 min `N=N_(0)e^(-lambdat_(2)) lambdat_(1)=ln 3` `2/3 N_(0)=N_(0)e^(-lambdat_(2)) ""t_(1)=1/LAMBDA ln 3` `2/3 N_(0)=N_(0)e^(-lambda t_(2))` `t_(2)=1/lambda ln 3/2` `t_(2)-t_(1)=1/lambda [ln 3/2-ln 3]` `=1/lambda ln [1/2]=(0.693)/(lambda)` |
|