Question 1

What is half-life?

Accepted Answer

Time for half of radioactive atoms to decay. Carbon-14: 5730 years. Iodine-131: 8 days.

Question 2

How do you calculate remaining activity?

Accepted Answer

A = A₀ × (1/2)^(t/t½). After 3 half-lives, 12.5% remains. After 10 half-lives, <0.1% remains.

Question 3

What's the difference between exposure and dose?

Accepted Answer

Exposure (roentgen) measures radiation in air. Absorbed dose (gray/rad) measures energy deposited. Equivalent dose (sievert/rem) accounts for biological effect.

Question 4

What are safe radiation levels?

Accepted Answer

Background radiation: ~3 mSv/year. Occupational limit: 50 mSv/year. Single dose effects start around 250 mSv. Always follow ALARA principle.

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