Radioactivity and Particles
3 marks · EasyA student measures the count rate from a radioactive source using a Geiger-Müller tube. The background count is 20 counts per minute. With the source in place, the count is 65 counts per minute.
Calculate the count rate due to the source alone.
Which unit should be used to record the activity?
Suggest one way to reduce your own exposure to this radiation during the experiment.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) 45 counts per minute
(b) Becquerel (Bq)
(c) Any one of: use tongs, increase distance, use lead shielding
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Subtracts background (65 - 20 = 45)
B1 (b) · 1 mark · States 'becquerel (Bq)' as correct unit
B2 (c) · 1 mark · Suggests a valid way to reduce exposure (any of: tongs, distance, shielding)
Worked solution
a) Subtract background: 65 - 20 = 45 counts per minute.
b) The activity should be recorded in becquerels (Bq).
c) Reduce exposure by using tongs, increasing distance, or using shielding.