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modern physics
Radioactive Decay & Half-Life
Watch a 3D sample of radioactive nuclei decay over time. See the exponential decay curve, calculate half-life, decay constant, and activity with a live Geiger counter display.
Half-Life
BothRadioactive decay is a random process. Each nucleus has a fixed probability of decaying per unit time. The half-life is the time for half the nuclei in a sample to decay. Activity A = λN follows an exponential decay law.
📐 Formulas
N = N_0 e^{-\lambda t}Number of undecayed nuclei
T_{1/2} = \frac{\ln 2}{\lambda}Time for half to decay
A = \lambda N = A_0 e^{-\lambda t}Decays per second
\lambda = \frac{\ln 2}{T_{1/2}}Probability of decay per unit time
📋 Syllabus
AQA4.4.2.3
EdexcelTopic 6