A teacher sets up a beta radiation source pointing towards a Geiger-Müller tube. The background radiation in the classroom has been measured as 22 counts per minute. The teacher then places a 5 mm thick sheet of aluminium directly between the beta source and the detector.
Estimate the count rate now recorded by the detector.
81 exam-style questions on Edexcel GCSE Physics 6.1 Atomic structure and isotopes. Each one has a worked solution and a mark scheme showing where the marks go.