Radioactive materials emit different types of radiation as they decay to become more stable.
- Alpha (α\alphaα) emission – A highly ionizing helium nucleus consisting of two protons and two neutrons, ejected from unstable heavy nuclei.
- Beta minus (β−\beta^-β−) emission – A fast-moving electron ejected from the nucleus when a neutron decays into a proton.
Write down two physical differences between alpha and beta minus emissions.
Explain how a magnetic field can be used to distinguish between alpha (α\alphaα), beta minus (β−\beta^-β−), and gamma (γ\gammaγ) radiation.
A student measures the total number of radioactive emissions (counts) from a long-lived cobalt-60 source over different time intervals. Because the source has an extremely long half-life, its activity remains constant throughout the duration of the experiment.
| Interval | Time (ttt, s\text{s}s) | Total Counts (NNN) |
|---|---|---|
| A | 5 | 115 |
| B | 10 | 230 |
| C | 15 | 345 |
| D | 20 | 460 |
Plot this data on a graph with Time (ttt, s\text{s}s) on the horizontal axis (0 to 25) and Total Counts (NNN) on the vertical axis (0 to 500), and draw a line of best fit.
Describe the relationship (pattern) between the time interval and the total counts shown on the graph.