1. Based on the figure below, radioactive activity after decay for 13.86 hours is …
Known :
Half-life (T1/2) = 6.93 hours
Time-lapse (t) = 13.86 hours
Wanted: radioactive activity
Solution :
A = radioactive activity, λ = the decay constant, Nt = The number of radioactive atoms after decaying during a certain time interval, T1/2 = half-life
The decay constant :
The number of radioactive atoms after decaying during a certain time interval :
Radioactive activity :
[irp]
2. Based on the figure below, after the radioactive substance decays for 15 minutes, then the remaining radioactive substance is …
Solution :
No = The initial amount of the radioactive atoms
Nt = The final amount of the radioactive atoms after decaying during a certain time interval (t)
t = time-lapse
T 1/2 = half-life
Calculate the Half-life :
Known :
No = 8 grams
Nt = 2 grams
t = 6 minutes
Wanted: half-life (T 1/2)
Solution :
Calculate the remaining radioactive material :
Known :
The initial amount of the radioactive atoms (No) = 8 grams
Time-lapse (t) = 15 minutes
Half-life (T 1/2) = 3 minutes
Wanted: the remaining radioactive material (Nt)
Solution :
[irp]
