1. Air.
Set the source up in a holder facing along the bench with the
Geiger tube in front of it.
You can test the range by moving the Geiger tube towards the
source and record when you notice a sudden increase in reading. You could plot a graph of
count rate against distance to show the effect of more air.
(a) alpha radiation – this only
has a short range (a few cm in air) and so the distances involved will probably be between 2
and 10 cm
(b) beta radiation – this has a much longer radiation in air and so the
distances involved will be between 50 cm and 10 cm
(c) gamma radiation – this has a
much larger range in air and so the distances involved will be from a 1m to 50 cm.
Of
course will all the radiations the range is not exact, especially for beta and gamma and you
may find it difficult to say exactly when the count rate increased.
2. Metals and other
solids
Set up the apparatus as before but this time put the Geiger tube close (a cm or so)
from the source.
Put different materials in between the source and the Geiger tube and
record the reading. If you have different thicknesses of the same material put them in one
after the other to get a graph of count rate against thickness.
The kind of materials I have
tried have been: aluminium, lead, iron, paper, wood, covering film, tissue paper, bacon (to
simulate flesh).
