Radioactive Decay & Half-Life Simulator
Classroom worksheet · Interactive simulation: https://lkforge.com/tools/physics/radioactive-decay/
Name: Date:
Learning objectives
- Define half-life and apply it.
- Describe decay as an exponential process.
- Relate activity to the number of remaining nuclei.
Variables to change
- Half-life
- Initial number of nuclei
Procedure
- Start with a full sample and step forward one half-life at a time.
- Record the fraction remaining after 1, 2, 3, and 4 half-lives.
- Observe how the activity (decays per second) changes over time.
Observations
Record the fraction of nuclei remaining after each half-life and how activity falls.
Questions
- What is a half-life?
- What fraction remains after 3 half-lives?
- Write the decay law.
- How does activity change as the sample decays?
- Can you predict when a specific atom will decay?
Answer key (instructors)
- 1. The time for half of the radioactive nuclei in a sample to decay.
- 2. One eighth (½ × ½ × ½).
- 3. N = N₀·(½)^(t/T½), equivalently N = N₀·e^(−λt).
- 4. It decreases over time, proportional to the number of nuclei remaining.
- 5. No — individual decays are random; only the statistical half-life of a large sample is predictable.
Radioactive decay is exponential: each half-life halves the remaining nuclei, so N = N₀·(½)^(t/T½). Activity falls in step with the number remaining. Individual decays are random, but the half-life makes large samples predictable — the basis of radiometric dating.