In the initial Rutherford scattering experiment Geiger and Marsden used α particles with an energy of 5 MeV. Choose a reasonable value for m0 and determine the range of angles for which (13.56) should be valid. Suggestion: Write m0=1/a, where a is a characteristic screening length. How large should a be? Note: Interaction with the electrons in the atom produces a deflection on the order of 10−4 radians.