What happens if t is greater than half-life?

  • #1
gabriellelee
21
1
Homework Statement:
What would be the difficulty in determining the activity of a source if the half-life is 1/3 shorter than the counting time,t?
Relevant Equations:
A(t) = A0e^(-lambda*t)
I tried plugging into the equation t = 3t1/2 and I got A(t) = 0.125A0 since -lambda*t = - ln(2)*t/(t/3) = -ln(2)*3.
So I understand that there will be 12.5% left of the original value since three half-lives have passed.
But then I realized this won't help me answer the question much.
So I'm thinking maybe it's because since the half-life is too short compared to the counting time, the majority of the activity will come from the daughter so it will be difficult to determine the initial activity of the source.
But I'm not sure if my thought process is right. Any help on this would be very much appreciated!
 

Answers and Replies

  • #2
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
2022 Award
39,165
8,487
I tried plugging into the equation t = 3t1/2
Why would you plug that in?
Do you understand what "1/3 shorter" means? What time is 1/3 shorter than 12 hours?
 
  • #3
gabriellelee
21
1
That was a typo. I meant t=(t1/2)/3
 
  • #4
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
2022 Award
39,165
8,487
That was a typo. I meant t=(t1/2)/3
Still wrong. Please answer my question in post #2.
 

Suggested for: What happens if t is greater than half-life?

Replies
18
Views
289
Replies
41
Views
717
  • Last Post
Replies
2
Views
323
  • Last Post
Replies
27
Views
2K
Replies
2
Views
339
  • Last Post
Replies
9
Views
77
  • Last Post
Replies
1
Views
601
Top