Decay constant — Science definition
Probability-rate parameter linking remaining nuclei to activity.
Where it is taught
- Half-Life Models & Nuclear Equations — Redox, Cells & Nuclear Chemistry, Physical Science: Chemistry, Grade 11
In use
Activity is proportional to the number of parent nuclei for a fixed isotope, with decay constant λ=ln 2/thalf.
Half-Life Models & Nuclear Equations
Questions using decay constant
Problem 1
If initial count is 1000 and decay constant is ln2/4 h⁻¹, find count after 8 h using N=N₀e⁻λt.
Hints
State what the supplied observations or conditions establish, and separate that from any assumption.
Answer and explanation
1000e⁻²ln2=250, equivalent to two half-lives.