Data : A (t1 ) = 1010 per hour, where t1 = 20 h,
A (t2) = 6.3 × 109 per hour, where t2 = 30 h
A(t) = A0 \(e^{-\lambda t}\)
∴ A(t1) = A0 \(e^{-\lambda t_1}\) and A(t2) = A0\(e^{-\lambda t_2}\)
∴ 1.587 e10λ ∴ 10λ =2.3031og10 (1.587)
∴ λ = (0.2303)(0.2007) = 0.04622 per hour
The half life of the material, T1/2 =
This is the initial number of radioactive atoms in the sample.