Radioactive Decay Calculator

Final amount (N): —

What is this calculator for?

This calculator helps you determine the remaining amount of a radioactive substance after a given time using its half-life. It's essential in nuclear physics, radiochemistry, archaeology (carbon dating), and medical applications.

How to use this calculator

  1. Enter the initial amount of the substance (N₀).
  2. Enter the elapsed time (t).
  3. Enter the half-life (T₁/₂) of the substance.
  4. The calculator will automatically compute the final amount remaining (N).

Formula

The formula used is:

N = N₀ × (1/2)t/T

Where:

  • N = final amount
  • N₀ = initial amount
  • t = time elapsed
  • T = half-life

Example

Suppose you have 1000g of a substance with a half-life of 5 years. After 10 years, how much remains?

Apply the formula:

N = 1000 × (1/2)10/5 = 1000 × (1/2)2 = 1000 × 0.25 = 250g

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