Question 25
FWater is leaking from a pipe buried under the ground.
Engineers add a small amount of a radioactive isotope to the water in the pipe. They move a detector along the ground above the pipe and record the count rate.
The Figure shows their results.
Figure
a.[1]
Use the Figure to identify the position of the leak.
b.[2]
Explain how the Figure shows the position of the leak.
c.[1]
The count rate is not zero at 0 m.
State why.
d.
[3]
The Table gives information about three radioactive isotopes.
Table
| Isotope | Radiation emitted | Half-life |
|---|---|---|
| P | alpha | 6 hours |
| Q | gamma | 15 hours |
| R | gamma | 30 years |
Explain which isotope is the most suitable for finding the leak.