A simple way to visualize Rutherford back-scattering.  

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Teachable Topics:

  • Nuclear Physics
  • Scattering Theory
  • Coulomb Repulsion 


In 1909, Ernest Rutherford and hi two students Hans Geiger and Ernest Marsden preformed an experiment to shoot alpha particles at thin gold foil. Rather than a slight deflection in the path of the alpha particles (as predicted by Thomson's 'Raisin cake' model of the atom), they found that many of the alpha particles were deflected at very large angles. This deflection, or scattering, is what is shown in the video.

Because alpha particles are positively charged, and were deflected at such large angles, Thomson's raisin cake model did not hold up. This led to Rutherford to think up a new model of the atom, one where all the positive charge is concentrated in the centre of the nucleus and the negative charges orbit around it. Thus the nuclear model of the atom was created! 


  • Overhead projector
  • Large and small ball bearings
  • Clear plastic sheet with frame


  • Place stand-in nucleus on the overhead projector.
  • Place the clear plastic sheet over top of the stand-in nucleus and projector.
  • Roll the smaller balls at various speeds towards the stand-in nucleus and watch what happens.


  • None

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