A radioactive source has a half-life of 3 hours.
A detector near the source shows a reading of 16,000 16,000\,16,000 counts per second.
Background radiation can be ignored.
What is the reading on the detector 12 hours later?
1,0001,0001,000 counts per second
2,0002,0002,000 counts per second
4,0004,0004,000 counts per second
8,0008,0008,000 counts per second
144 exam-style questions on CIE IGCSE Physics 5.2.4a Half-life. Each one has a worked solution and a mark scheme showing where the marks go.