Half Life Calculators? Find one online to help with your physics, nuclear or radioactive decay study. Half-life is the time required for a quantity to reduce to half its initial value. It is the opposite of doubling time and is an exponential equation. Half-life can also be used in biology to determine how long a substance stays in the human body.

What is the definition of a half-life?

Find Free Online Half-Life Calculators. A half-life is the amount of time it takes for a given quantity of a substance to decrease to half of its original amount/value. The term half-life is commonly used to define how long radioactive substances take to decay to half their initial amount.

Where did the term half life come from?

Ernest Rutherford a New Zealand physicist coined the term half-life period in 1907 when studying the decay of the element radium. This term was later shortened to half-life

What is the half life of some elements

• Uranium 238: 4.5x10⁹ years
• Plutonium 239: 2.4x10⁴ years
• Radon 220: 52 seconds