Question 1
The dashed line on the graph shows the decay curve recorded from a sample of a particular radioactive isotope. The count rate includes background radiation.
Which curve shows the corrected count rate for the decay?
Question 2
A student is investigating the count rate of a radioactive substance.
How must he adjust his reading for the background count?
A
Add the background count to his reading.
B
Ignore the background count as it will not affect his reading.
C
Subtract the background count from his reading.
D
Take repeat readings to eliminate the background count.
Question 3
A radioactive isotope has a half-life of 8 days.
A detector close to a sample of this isotope gives a count rate of 200 counts per minute.
Without the source, the background count is 20 counts per minute.
What is the count rate due to the source after 8 days?
A
80 counts per minute
B
90 counts per minute
C
100 counts per minute
D
110 counts per minute
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