1. The problem statement, all variables and given/known data Plutonium-238 with a half-life of 90 years, emits and alpha particle of energy 5.10 MeV. 180mg of this radioisotope is used to power a pacemaker. Calculate the initial power in mW, supplied by Plutonium-238, assuming a 100% efficiency for the conversion of decay energy into usable power. 2. Relevant equations I tried using: N = No(1/2)^(t/T), where T is the half-life P = W/t 3. The attempt at a solution I do not know what "time" to use in order to calculate the power. What does it mean by "initial"? Help would be very appreciated.