29. Let tbe the present time and t= 0 be the time when the ratio of 235U to 238U was 3.0%. Let N235be the number of 235U nuclei present in a sample now and N235, 0be the number present at t= 0. Let N238be the number of 238U nuclei present in the sample now and N238, 0be the number present at t= 0. The law of radioactive decay holds for each specie, so NNet235235 0235=−,λand et238238 0=−,.λ238Dividing the first equation by the second, we obtain rret=−−0()λλ235238where r = N
This is the end of the preview. Sign up
access the rest of the document.