An isotope has an initial activity of 120 Bq 6 ... - JAMB Physics 2022 Question

Here's how to solve this problem:

1. Understand Half-Life: Half-life is the time it takes for the activity of a radioactive substance to reduce by half.

2. Determine the Number of Half-Lives: The activity decreased from 120 Bq to 15 Bq. Let's see how many half-lives this represents:

   • 120 Bq -> 60 Bq (1 half-life)
   • 60 Bq -> 30 Bq (2 half-lives)
   • 30 Bq -> 15 Bq (3 half-lives) So, there were 3 half-lives.

3. Calculate the Half-Life: The total time