The decay constant of a radioactive nuclide is 3.1 x $10 ^{- 3}$ $\mathrm { s } ^ { - 1 }$ At a given instant,the activity of a specimen of the nuclide is 70 kBq.How much later has the activity declined to 10 kBq?

Question

Quizplus · Accepted Answer

The activity of a radioactive substance decreases exponentially over time according to the formula $ A = A_0 e^{-\lambda t} $. Given $ A_0 = 70 $ kBq, $ A = 10 $ kBq, and $ \lambda = 3.1 \times 10^{-3} $ s$^{-1}$, solving for $ t $ gives approximately 630 s.

The Decay Constant of a Radioactive Nuclide Is 3 10−310 ^{- 3}10−3

The Decay Constant of a Radioactive Nuclide Is 3 $10 ^{- 3}$