Recent content by sweminka

"only 5% of the particles are detected" This sentence suddenly made everything clear to me. I guess I couldn't understand the meaning of "efficiency". Anyway, I replaced 6000 by 120 000 (100%) in my calculations, and I find the correct answer. Thank you very much :)

The answer is supposed to be 2*10^(-7) though :( I guess it has something to do with the detector's efficiency ?

Here are my calculations : N(t)=No*exp(-λt) 10^10 - 6000 = (10^10) * exp (-λ*60) ( 10^10 -6000) / (10^10) = exp (-λ*60) ln ( ( 10^10 -6000) / (10^10) ) = -λ*60 λ= ( - ln ( ( 10^10 -6000) / (10^10) ) ) / 60 λ = 10*(-8) per second

A piece of radioactive substance gives a received count rate of 6000 counts per minute in a detector whose efficiency is known to be 5%. If the sample contains 10^10 atoms, what is the decay constant ( λ ) of this radioactive substance ? No idea how to solve this problem. Any help would be...