CBSE Class 11-science Answered

In RUTHERFORD EXPT,

      the assumptions were that the observed scattering of alpha particals came from single encounters  with nuclei and assuming that the force was just the electrostatic rerpulsion.

 

Rutherford found scattering angle as a function of ingoing speed and impact parameteris given bu :

         

However when Aluminium foil was used ,although small scattering were following the rule while greater angle scattering didnt because in larger angle scattering which correspond to closer approach to the nuclei the partical was actually hitting the nucleus,that is size of the nucleus can be found bu finding the maximum angle for which inverse square of scattering formula worked.