Half life of a radio active element

[logearav]

Homework Statement

The half life period of N-13 is 10.1 minute. Its life time is -------
The answer has been given as infinity.
Could someone help the formula to arrive at this answer
2. The time taken by the radio active element to reduce 1/e times is -----
The answer has been given as Mean Life.
How this answer comes?
Please help, revered members.

Homework Equations

The Attempt at a Solution

 

[tiny-tim]

hi logearav!

if the half-life is H, then the three-quarter-life (ie, the time for three-quarters to decay) is 2H, and so on … the full-life will be ∞ times H

you should be able to answer your 1/e problem by using the standard decay equation …

see the PF Library on https://www.physicsforums.com/library.php?do=view_item&itemid=193&pagenumber=1" for some details

 

[logearav]

thanks tiny-tim. for the second question i put N = N0 / e AND GOT THE ANSWER. THANKS AGAIN