Example 1
After two half-lives, 25% of the initial nuclei remain.
Mendeleev
Physics tools
All toolsElements
EnglishEN⌄
Languages
EnglishENFrançaisFRDeutschDEEspañolESItalianoITPortuguêsPTNederlandsNLPolskiPLSvenskaSVČeštinaCSDanskDANorskNOSuomiFITürkçeTRРусскийRUУкраїнськаUK中文ZH日本語JAБългарскиBGCatalàCAΕλληνικάELEestiETHrvatskiHRMagyarHULëtzebuergeschLBLietuviųLTLatviešuLVRomânăROSlovenčinaSKSlovenščinaSLСрпскиSR한국어KOTiếng ViệtVIBahasa IndonesiaIDBahasa MelayuMSالعربيةARहिन्दीHIไทยTHעבריתHEÍslenskaIS
Physics tools › Radioactive decay
Mendeleev · Physics
Radioactive decay
Radioactive decay reduces the number of undecayed nuclei by half during each half-life.
Formula usedN = N₀·2^(−t/T½)
Visual cue · nuclei remaining
Calculate
Radioactive decay
What do the symbols mean?
Nremaining amount
N₀initial amount
Δtelapsed time
T½half-life
Two worked examples
Example 2
An initial amount of 800 reduced through three half-lives leaves 100 in the same arbitrary amount unit.
Good to knowThe law describes the expected evolution of a large population of identical radioactive nuclei; individual decay events remain random.