Sharp EL-5250 User Manual
97
Radioactive decay
Carbon-14 (
14
C) is a naturally occurring radioactive isotope of carbon used in
the carbon dating process. Because carbon-14 decays at a steady rate, it is
possible to determine the age of a once living specimen by measuring the
residual amount of
possible to determine the age of a once living specimen by measuring the
residual amount of
14
C it contains.
Example
This program asks for a original mass and current mass of
14
C and tells you
how old the specimen is. It then finds the half-life of
14
C.
1.
Press b 2 1 0 to open a window for creating a NEW
program.
program.
2.
Type DECAY for the title then press
e.
e.
• A NEW program called ‘DECAY’ will be
created.
3.
Enter the program as follows.
Program code
Key operations
Print”ORIGINAL MASS
i 1 @ a ORIGINAL s
MASS
MASS
; e
Input M≠
i 2 @ v M0 e e
e
e
Print”CURRENT MASS
i 1 @ a CURRENT s
MASS
MASS
; e
Input M≥
i 2 @ v d M1 e
e e
e e
Chapter 8: Application Examples
The mass of
14
C contained in a sample changes according to the
equation
M = M
0
e
–kt
or t = –––––––––
where M
1
= Mass of
14
C at time t
M
0
= Original mass of
14
C
k = Radioactive decay constant (for
14
C, k = 1.2118
× 10
–4
year
–1
)
t = Elapsed time in years
M
1
M
0
k
–ln ( ––– )
DECAY :NORMAL
PROGRAM?
PROGRAM?