Calculateur de Section Efficace
Calculez la section efficace d'une réaction nucléaire.
Amount Remaining
3.1250
Amount Remaining vs Initial Amount
Formule
## Remaining After n Half-Lives Each half-life reduces the remaining amount by half. After n half-lives, the fraction remaining is (1/2)^n. ### Formula **N = N0 × (1/2)^n** This applies to radioactive decay, drug elimination, chemical degradation, and any first-order process.
Exemple Résolu
Starting with 100 grams, after 5 half-lives.
- 01Remaining = 100 × (0.5)^5
- 02Remaining = 100 × 0.03125 = 3.125 grams
- 03Only 3.125% remains after 5 half-lives
Questions Fréquentes
How many half-lives until less than 1% remains?
After 7 half-lives: (0.5)^7 = 0.78% remains. So 7 half-lives reduces the amount to less than 1% of the original.
Does this work for drug elimination?
Yes. Drugs eliminated by first-order kinetics follow the same math. A drug with a 4-hour half-life is essentially gone after 5-7 half-lives (20-28 hours).
Can n be a fraction?
Yes. After 2.5 half-lives, the remaining fraction is (0.5)^2.5 = 0.177 = 17.7%. The formula works for any non-negative value of n.
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