For 1000k atoms I will have a 500k after 1 half life, and 250k after 2 half lives. But when I try to do the same with fractions something doesn’t add up. Because after “quarter life” i will have 750k atoms, but then I’ll have 562500 atoms, because of 750k multiplied by 0.75. So quarter life should be equal to 0.5 of half life, but half life doesn’t work that way. I am confused.
In: Physics
The whole “2 quarter lives isn’t 1 half life” thing has been well explained, but I wanted to point out that other fractional-lives are used a lot. In many applications (one big one being electrical engineering) you’ll run into something similar to half-life called the ‘time constant’ τ which a measure of the time it takes for ~63.2% (1 – 1/e) of the thing to happen. This value is chosen because it can make some kinds of math a lot easier to do.
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