half life

• What is the half-life of a radioactive isotope?


  The time it takes for half the original nuclei to decay
• If a radioactive isotope has a half-life of 20 minutes, how long will it take for 1,000 undecayed nuclei to reduce to 500 nuclei?


  20 minutes
• How can you determine the half-life of an isotope from a graph?


  By finding the time it takes for the number of undecayed nuclei to fall to half
• What does the count rate refer to in radioactive decay?


  The number of decays per second recorded by a detector
• What happens to the count rate after each half-life?


  It halves
• If a radioactive isotope has a half-life of 15 days and an initial count rate of 200 counts per second, what will the count rate be after 45 days?


  25 counts per second
• How does the decay rate of a radioactive isotope with a long half-life compare to one with a short half-life?


  A long half-life indicates a slower decay rate
• What can be inferred about a radioactive isotope that decays quickly?


  It has a relatively short half-life
• If the count rate of a radioactive isotope is 200 counts per second and it has a half-life of 15 days, what will the count rate be after 30 days?


  50 counts per second
• What is the significance of the Geiger-Müller tube in radioactive decay?


  It detects the count rate of decays
• What does it mean when it is said that decay is a random process?


  It means that the exact time of decay for individual nuclei cannot be predicted
• How does the concept of half-life help in understanding radioactive decay?


  It provides a measurable way to quantify the rate of decay
• If a sample has 1,000 undecayed nuclei and the half-life is 20 minutes, how many nuclei will remain after 60 minutes?


  125 nuclei
• What is the relationship between half-life and the decay rate of a radioactive isotope?


  A shorter half-life indicates a faster decay rate
• How can the half-life of an isotope be visually represented?


  Through a graph showing the number of undecayed nuclei over time
• What does a decrease in count rate indicate about a radioactive sample?


  It indicates that the number of undecayed nuclei is decreasing