Suppose that an alpha particle in Geiger and Marsden's experiment had been fired at a gold nucleus head-on and was scattered backwards (through an angle of 180∘ ).
If the alpha particle began with 5 MeV of kinetic energy, determine the maximum size of a gold nucleus.
Data:
- a gold nucleus has 79 protons
- k=9×109 Nm2C−2 , 1 eV=1.6×10−19 J
- the charge on a proton is 1.6×10−19 C