Question

3. (a) Write down the exponential law of radioactive decay. How would you deduce the (20 marks) half-life from this formula? (b) A radioactive source has an activity of 1.5 u Ci att-0. Its half-life is 2.0 hour (i) How many nuclei are present at 0? (10 marks) (10 marks) (c) Spontaneous emission of an α particle in mRa can be presented by the (i) How many decays occur between t0 andt-2 hour? following process ) Calculate the net energy released in the decay, the Q-value of Ra (10 marks) (ii) Sketch the graph of the potential energy between the α particle and the (20 marks) residual nucleus at distance r (ii) Calculate the Gamow factor, G for the same nucleus 20 COS where a 7.27 fm and the height of the Coulomb barrier is given as SMES3201 nE a (30 marks)

Answer 1

iven o activity : 1.5 서じ 2-0 hour half lfe fraim also t n 1/2. 2 2. 0 692 0 3465 1-S 0.3465 N = O 3465 C3

otuoing be tween t0 tot 2 m ejua pon t- 2 t-o Subsh utng values に。 - 0.341 2 NLt)= 2 0.so66 2 NLt)- 01 Decay occurin