Final answer:
The extent of activity in a domain at a point in time is determined by the quantity of material, the half-life, and the distance from the source.
Step-by-step explanation:
The extent of activity in a domain at a point in time is determined by several factors:
- The quantity of material: The activity of a source depends on the amount of material present. A larger quantity of material will result in a higher activity.
- The half-life: The activity also depends on the half-life of the material. A shorter half-life will produce more disintegrations per second and therefore a higher activity.
- The distance from the source: A high level of activity may not be significant if a person is far away from the source. The activity decreases exponentially as the distance increases.
These factors can be seen in various domains, such as radioactive decay and population dynamics.