Half-Life
Part of the Optics, Waves and Modern Physics section of Coddy's Physics journey. Lesson 46 of 53.
Each nucleus decays at random; half of them decay in one half-life T.
N = N₀ (½)^(t/T)
After n half-lives: (½)ⁿ is left. 3 half-lives: 1/8.
Challenge
A radioactive sample has a mass of 80 g and a half-life of 5 days. How much of it m is left after 15 days?
Try it yourself
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Optics, Waves and Modern Physics
1Reflection and Refraction
Reflection of LightThe Refractive IndexSnell's LawTotal Internal ReflectionDispersionApparent DepthRecap - Optical Fiber4Mechanical Waves
What a Wave IsTwo Graphs of a WaveWhen Pulses MeetInterferenceStanding WavesHarmonicsRecap - Guitar String3Thin Lenses
Lenses and Their RaysThe Lens EquationVirtual ImagesTwo LensesA Lens and a MirrorRecap - Build a Projector6Light as a Wave
Light Through Two SlitsFringes on a ScreenDiffraction by One SlitThe Diffraction GratingRecap - Measure with a CD9The Nucleus
Inside the NucleusRadioactive DecayHalf-LifeActivityRadioactive DatingRecap - Carbon Dating