Rutherford Scattering

This simulation recreates the gold foil experiment that revealed the atomic nucleus. Alpha particles follow real Coulomb repulsion paths past a tiny dense nucleus, with trail colour showing the deflection from blue for small to orange for large. Students set the alpha energy, the width of the beam and the target nucleus: gold, silver, copper or aluminium. Readouts give closest approach, the last alpha's aim and angle, and how many turned through more than 90 degrees. It helps explain why the nuclear model replaced the plum pudding model.

• Run the beam on Gold and note which alpha paths are bent the most, then read the Last alpha readout.
• Raise Alpha energy from 5.5 to 9 MeV and see how Closest approach d0 gets smaller.
• Switch Target nucleus to Aluminium and compare the amount of deflection with gold.
• Narrow Beam half-width and watch how many more alphas pass close to the nucleus.
• Watch the Turned more than 90 degrees counter and discuss why it is so rare.

1. 1Describe Rutherford's gold foil experiment and what it revealed.
2. 2Explain why a few alpha particles scatter through large angles.
3. 3Relate scattering angle to the aim, or impact parameter, of the alpha.
4. 4Compare how nuclear charge and alpha energy affect deflection.

Questions teachers ask