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One gram of carbon from a wooden bowl gives 7.0 decays per minute from carbon-14…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
One gram of carbon from a wooden bowl gives decays per minute from carbon-14. One gram of carbon from a living tree gives decays per minute. The half-life of carbon-14 is years. Find the age of the bowl, and the number of half-lives that have passed.
Need a reminder? The key ideaShow
The activity of a sample falls as , so the age is . For uranium-lead dating, , with numbers of atoms. A year is s.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The ratio. .
Step 2. The number of half-lives. .
Step 3. The age. y.
Answer: years, which is half-lives.
Check. A bit more than one half-life, with a bit less than half the activity left. It fits.
Source. The value decays per minute for each gram of living carbon is the figure used in many textbooks. Modern measurements give a lower value, about . The problem states the number that it uses.
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