Re: Practical demonstration of a half-life

["Richard C. Mannix" <rcmannix@uci.edu>]

I once used the "cutting-up-the-pie" approach at a grammar school.

It was around Thanksgiving, so I used a pumpkin pie. I told the kids that
in one half-life, the amount of radioactive atoms would be reduced to
one-half of the original number. I cut the pie in half.

Then, I told them that in one more half-life, the amount of radioactive
atoms left would be reduced by one-half, so I cut the half pie in half.

Then I cut the quarter pie in half, and so on until the amount left was
below the "resolution" of my butter knife. At the end, all of the pieces
were lined up next to each other to show that the amount of pie remaining
after each half-life was one-half of size of the piece before it, and that
the amount of pie left never went to zero.

The best part of this demo is that we all pigged out on the pie after the
class. I got stuck with the smallest piece, darn it...

Rick Mannix
Health Physicist
Laser Safety Officer
Univ. of Calif., Irvine
949-824-6098
rcmannix@uci.edu
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