In a laboratory, a detector of ionising radiation records an average background count rate of 15 counts/s15\text{ counts/s}15 counts/s.
A radioactive source is now placed close to the detector. The count rate on the detector rises to 320 counts/s320\text{ counts/s}320 counts/s.
What is the count rate due to radiation from the radioactive source?
21.3 counts/s21.3\text{ counts/s}21.3 counts/s
305 counts/s305\text{ counts/s}305 counts/s
320 counts/s320\text{ counts/s}320 counts/s
335 counts/s335\text{ counts/s}335 counts/s
44 exam-style questions on CIE IGCSE Physics 5.2.1 Background radiation and measuring count rate. Each one has a worked solution and a mark scheme showing where the marks go.