a) Consider a person of 70 Kg. 0.20% of the body mass ispotassium and it is a vital nutrient. Natural potassium (mostly39K and 41K) also contains 0.012%40K with a half- life time of 1.3 billion years.40K emits a β- of average energy of 58.5 keV in 89.3% ofits decays and a 1.461 MeV γ-ray in 10.7% of the decays. How manyof these high-energy γ-rays is generated in the person persecond?
b) If you assume that all the energy from the electrons andγ-rays is absorbed in the body, what is the effective dose for theperson in one year?
c) While nowadays 0.012% of all potassium is 40K,what was its share of all potassium 4.5 billion years ago, when theEarth formed?
