half life (science)

• What is the definition of half-life?


  Time for half of a radioactive substance to decay
• How can half-life be explained to a five-year-old?


  It's the time for half of magical rocks to vanish
• What is the process of half-life using a cake analogy?


  • Start with a whole cake
  • After one half-life, half the cake is left
  • After another half-life, a quarter of the cake remains
• In which fields is half-life applied?


  Radioactive materials, medical tracers, carbon dating
• What does exponential decay mean in the context of half-life?


  Substance reduces by half repeatedly over time
• How does exponential decay work with a magical balloon analogy?


  • Balloon shrinks by half each time
  • Continues shrinking but never fully disappears
  • Similar to eating cookies: half, then half again
• What is the general formula for calculating half-life?


  $t_{1/2} =$$\frac{0.693}{\lambda}$
• What does the decay constant represent in the half-life formula?


  It is a special number used in calculations
• If the decay constant is $λ =$$0.05$, what is the half-life?


  $t_{1/2} =$$13.86$
• How do you calculate half-life using the formula?


  Identify decay constant, substitute, calculate
• If a substance has a decay constant of $λ =$$0.003$, what is its half-life?


  $t_{1/2} =$$231$
• What are some applications of half-life in different fields?


  • **Radioactive dating**: Carbon-14 dating fossils
  • Medical tracers: Iodine-131 in thyroid studies
  • Nuclear medicine: Cobalt-60 in cancer treatment
  • Nuclear power: Uranium-238 in reactors
• How is half-life used in archaeology?


  To determine the age of dinosaur bones
• How does half-life help in medical applications?


  It uses tracers to find hidden problems
• How does half-life assist volcano scientists?


  To understand the age of rocks
• How is half-life relevant in space exploration?


  To understand material changes in space
• If a radioactive substance has a decay constant of $\lambda =$$0.03$, what is its half-life?


  $t_{1/2} =$$23.1$
• How do you calculate the half-life of a substance with a decay constant of $\lambda =$$0.001$?


  $t_{1/2} =$$693$
• Iodine-131 (I-131)


  Used as a medical tracer in thyroid studies. Half-life: 8 days.
• Iodine-135 (I-135)


  Not commonly used as a medical tracer. Half-life: approximately 6.57 hours (shorter than I-131).
• Half-Life


  The time it takes for half of a radioactive substance to decay.
• Radioactive Dating


  Carbon-14 dating is an example of radioactive dating.
• Medical Tracer


  1. 131 is used as a medical tracer in thyroid studies.
• Nuclear Medicine


  Cobalt-60 is used in nuclear medicine for cancer treatment.
• Nuclear Power


  Uranium-238 is used in nuclear power reactors.
• Half-life


  The time it takes for half of a radioactive material to decay.
• 14C (Radiocarbon)


  A radioactive isotope of carbon used in radiocarbon dating to estimate the age of organic materials.
• Radiocarbon dating


  A method used to determine the age of organic materials by measuring the amount of 14C remaining.
• Principle of radiocarbon dating


  The amount of 14C in an organic material decreases at a constant rate over time, used to calculate its age.
• Limitations of radiocarbon dating


  Only effective for dating materials up to 50,000 years old and not suitable for fossils, charred bones, or minerals.