LAB VIIIi: RADIOACTIVE
DECAY
Problem: What is the relationship
between the amount of radioactive decay and the time allowed for
decay?
Materials: 100 die, graph
paper,
Procedure: the 100 die
represent 100 radioactive iodine124 atoms. Place the 100 die
into a paper bag and shake them up. Shake them out of the bag.
Each die showing a number 1 face up represents an atom that has
decayed. Remove all the atoms that decayed for the first toss
(day one). Put the rest of the die back in the paper bag and shake
them up again. Repeat the process for the second toss (representing
day 2).
Results:
Complete the
following table:
Time (days) Atoms
remaining
0 100
1 ___
2 ___
3 ___
Continue till
all atoms have decayed. This may take approximately 25 steps.
A) How long did
it take for half the atoms to decay from 100 to approximately
50?
B) How long did
it take for the atoms to decay half again (from about 50 to about
25?
C) How long did
it take for the atoms to decay half again?
D) What is the
average of the values in A , B and C?
If the equation
of your data is approximately:
y = 100(0.83^{x})
Discussion:
1) What are the
independent and dependent variables?
2) How are the
variables changing with relationship to each other?
3) What happens
to the dependent variable when the independent variable increases?
decreases?
4) How does the
relationship shown in this experiment compare with other relationships
you have so far seen?
5) How does the
equation for this relationship compare with those of other equations
you have studied?
6) What is the
meaning of halflife in a radioactive substance?
7) What is the
approximate halflife of your experiment?
