An environmental officer uses a portable radiation survey meter to monitor radiation levels at a site.
Before testing any soil samples, she sets up the meter in her vehicle parked far away from the site.
With no soil samples nearby, the survey meter records 84 counts over a 3-minute period.
State why the survey meter still records a reading when no samples are present.
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.