And, if we wait one more half-life, then that would go to 0.25 milligrams.
We wait one half-life, goes to two milligrams. We're starting with four milligrams, so one very simple way of doing this is to think about what happensĪfter each half-life. So, how many half-lives is that? 57.2 days divided by 14.3 days would give us how many Milligrams of phosphorus-32, how much is left after 57.2 days? So if you're waiting 57.2 days, well, the half-life of Number of half-lives, you can see the amount of radioactive material is decreasing. We'll talk a little bit more about exponential decay in the next video. That's what we're talking about when we're talking about Right, so if I think about this graph, this is exponential decay. And we could keep going, but this is enough to give you an idea And what's half of one? It's 0.5, of course, so, in here, that's about 0.5, and so that gives us an idea about where So after 28.6 days, we should have one milligram of our sample. So we know that after 28.6ĭays, it's another half-life, so what's 1/2 of two, it's one, of course. Alright, we wait another 14.3 days, so we wait another half-life, so after two half-lives, that should be 28.6 days. There should be two milligrams left after 14.3 days so that's our point. We wait 14.3 days, so this is 14.3 days, and half of our sample should be left. This off so this would be one milligram, two Alright, we're going to start with four milligrams of our sample. On the X-axis, let's do time,Īnd since the half-life is in days, it just makes itĮasier to do this in days. On the Y-axis, let's do the amount of phosphorus-32, and we're working in milligrams here, so this will be in milligrams. Phosphorus-32 in this video, and we're going to actually start with four milligrams every time in this video just to help us understand It's approximately 4.47 times 10 to the ninth, in years. Something like uranium-238, the half-life is different, And it took 14.3 days for this to happen. So, if we start with four milligrams, and we lose 1/2 of that, right, then we're left with two milligrams. It's the time it takes for 1/2 of your radioactive nuclei to decay. Let's look at the definitionįor half-life here. And we wait 14.3 days, and we see how much of Here's our beta particle, and the phosphorus is going to turn into sulfur. So we talked about betaĭecay in the last video.
Phosphorus-32 is radioactive and undergoes beta decay.
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