00:01
Right now we are looking at the radioactive decay of oxygen and 19.
00:08
15, oxygen 19.
00:10
With their respective t - halves, or their half -lives, right, let me just put them as t -15 and t -19 for now.
00:20
So we know that the initial amount of t -15, right, t equals to 0, is equal to the amount of oxygen -19.
00:35
It's given the equation in the question.
00:39
And after some time t, we are now given that it is twice, right? the oxygen 15 now has twice the amount compared to oxygen 19.
00:56
And we want to find what is this time t.
01:01
So first of all, we can write down the decay rate equation.
01:05
For n15 at time t is equal to the original amount multiplied by half to the power of the number of half lives that has passed right and to find a number of half life that has passed we just take t divided by the half life same thing we can do for oxygen 19 also the same values except now it's the t half for oxygen 19 simple.
01:41
Now from the first equation, we know that the original amount, which is underlined here, they are the same.
01:50
So if you divide this, they will cancel out, right? they will be 1.
01:55
And if we, from the second equation, we know that if we divide n15 at time t with n 19 at time t, you will get 2...