Physics help!!

[MrKiller009]

Hi,
Can someone explain to me what's meant by half-life? i really dont get it
would be helpful if you have notes on that part!
thanks in advance .

 

[Rimsa]

The process in which an element loses half of its energy cuz of continous radioactive emission. Its called radioactive half life decay! Half life can vary from few secs to thousands of years! We know its half when GM counter gives half of initial reading.
100 counts/ min___20 hours____> 50 counts/min ___20hours____> 25 counts/min