1. What is Amount of Substance Left After Two Half Lives?

Definition: This is the quantity of radioactive substance remaining after it has undergone two half-life periods.

Purpose: It helps in determining how much radioactive material remains after specific time periods, which is crucial in nuclear physics, medicine, and radiocarbon dating.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( N_t(2) \) — Amount left after two half-lives (kg)
• \( N_0 \) — Initial concentration of radioactive substance (kg)

Explanation: After one half-life, half of the substance remains. After two half-lives, one quarter (1/4) of the original amount remains.

3. Importance of Half-Life Calculations

Details: These calculations are essential for determining the safety and effectiveness of radioactive materials in medical treatments, nuclear power generation, and archaeological dating.

4. Using the Calculator

Tips: Enter the initial concentration of the radioactive substance in kilograms. The value must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why does the amount quarter after two half-lives?
A: Each half-life reduces the amount by half, so two half-lives reduce it to (1/2) × (1/2) = 1/4 of the original amount.

Q2: What's the difference between one and two half-lives?
A: One half-life leaves 50% of the substance, while two half-lives leave 25%.

Q3: Does this apply to all radioactive substances?
A: Yes, the half-life principle applies universally, though the actual half-life duration varies between substances.

Q4: How precise are these calculations?
A: The calculations are mathematically precise, assuming you know the exact initial amount and the substance follows perfect exponential decay.

Q5: Can I calculate for more than two half-lives?
A: Yes, for n half-lives, the remaining amount is \( N_0 \times (1/2)^n \).