# The activity of a radioactive element will decrease by 4 times in 10 days. What is the half-life?

September 25, 2021 | education

| To find the value of the half-life of the taken radioactive element, we use the formula: N / N0 = 2 ^ -t / T.

Variables: N0 / N – change in the activity of the taken radioactive element (N0 / N = 4 and N / N0 = 1/4); t – elapsed time (t = 10 days).

Calculation: N / N0 = 2 ^ -t / T; 1/4 = 2 ^ -10 / T; 2-2 = 2 ^ -10 / T; 2 = 10 / T and T = 10/2 = 5 days.

Answer: The half-life of the taken radioactive element is 5 days.

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