A student measures the activity of a radioactive source by placing different materials between the source and the detector. The recorded activities are as follows: with air only, the activity is 820 counts per minute820\text{ counts per minute}820 counts per minute; with a sheet of paper, the activity is 815 counts per minute815\text{ counts per minute}815 counts per minute; with 5 mm thick aluminium, it is 230 counts per minute230\text{ counts per minute}230 counts per minute; and with 20 mm thick lead, it is 25 counts per minute25\text{ counts per minute}25 counts per minute.
Which type of radiation is emitted by the radioactive source?
Alpha particles only
Beta particles and gamma rays only
Alpha and beta particles only
Gamma rays only
41 exam-style questions on OCR GCSE Physics Radioactive emissions. Each one has a worked solution and a mark scheme showing where the marks go.