Activity

Definition

Activity is the measure of the number of radioactive decays per unit time in a given sample. It is typically measured in becquerels (Bq) or curies (Ci).

5 Must Know Facts For Your Next Test

1. The SI unit for activity is the becquerel (Bq), which corresponds to one decay per second.
2. Activity decreases over time as a result of radioactive decay, following an exponential decay law.
3. It can be calculated using the equation $A = \lambda N$, where $A$ is the activity, $\lambda$ is the decay constant, and $N$ is the number of undecayed nuclei.
4. The relationship between half-life ($T_{1/2}$) and decay constant ($\lambda$) is given by $\lambda = \frac{0.693}{T_{1/2}}$.
5. Knowing the activity helps in determining the safety and usage of radioactive materials in practical applications.

Review Questions

• What is the SI unit for measuring activity?
• How does activity change over time for a radioactive substance?
• Write down the formula that relates activity ($A$), decay constant ($\lambda$), and number of undecayed nuclei ($N$).

Related terms

Half-Life: The time required for half of the radioactive nuclei in a sample to undergo decay.

Decay Constant:

A parameter that represents the probability per unit time that a nucleus will decay.

Becquerel:

The SI unit of radioactivity, defined as one disintegration per second.