2011 question 24:
A radioactive source emits a parallel beam of alpha, beta and gamma radiation
and is placed 10 cm from a detector, which is sensitive to all forms of radiation
and receives 100 counts/sec.
When a sheet of aluminium of thickness 1 cm is placed in front of the detector,
the radiation level is seen to fall to 50 counts/sec.
When the source is taken away completely, the radiation levels are seen to
fall to 10 counts/sec.
When the source is placed 1 cm from the detector, the radiation levels are
seen to increase to 400 counts/sec.
In what proportion is the source emitting alpha:beta:gamma particles?
Have seen this type of questions in other past papers. Thought I could skip it every time but this time its a 4 mark question instead of one in the multiple choice part. Slightly worried now since the test is in a day's time.