1. The problem statement, all variables and given/known data A radioactive source emits alpha particles at a constant rate 3.5x10^6 s^-1. The particles are collected for a period of 40 days. BY reference to the half life of the source, suggest why it may be assumed that rate of emission of alpha particles remain constant? 3. The attempt at a solution Since the decay constant is very small, ##A_o-A \approx A_o## where ##A_o## is initial activity and ##A## is a decrease in activity over a significant period of time. Since Activity remains constant, the rate of emission remains constant. I cannot, however, find a way to incorporate the half-life into the answer which the question specifically mentions. I am aware of the relation between decay constant and half-life, but for this situation, I cannot develop a clear logic which involves the half-life of the source. More specifically how does rate of emission remains constant if a half-life is high? Secondly, how do I know half life is high in this question? Thirdly, what is the significance of the provided period of 40 days?