How many half-lives (n) will it take a source to decay by a factor of 1/512? [Re

Question

      How many half-lives (n) will it take a source to decay by a factor of 1/512? [Recall: Cn=C0(1/2)^n = Co/512] Use your measured value of Th and calculate the Ba-137m counts (Cnet) you expect after n half-lives. I have seen this question on here and have seen that they get an answer of 9 for the first part. I don't know how to get the answer of 9. Also, to calculate the counts expected after the half-lives, is it the equation of Cn=(1/2)^n * C0? So, with my numbers, Cn=(1/2)^n * 849? Thanks for any help anyone can give. Physics is just not something that comes easy to me. :(

Explanation / Answer

512 = 2^9

i.e after 9 half lives, a source decays by a factor of 1/512..

From definition, Half-life is the time required for a quantity to fall to half its value as measured at the beginning of the time period

After one half life, its concentration decreases to half..

after second, it decreases to 1/4.. and so on..

and after 9 hl's it reduces to 1/512..

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.