SACE Stage 2 Physics — Light & Atoms 3.3

Rutherford Scattering

A collimated beam of alpha particles is fired at a thin metal foil. A phosphor-coated screen wraps around the foil and glows wherever an alpha lands. Switch the atomic model between Thomson's plum pudding (positive charge spread through the whole atom) and Rutherford's nuclear model (positive charge concentrated at a point) and compare the glow patterns each predicts.

Atomic model

Target foil

Alpha energy

E MeV

Beam

Rate α/s

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Counts

Fired0

Forward (θ < 20°)0 (0.0%)

θ > 90°0 (0.0%)

θ > 150°0 (0.0%)

Diagrammatic. Back-scatter rate exaggerated so rare events appear within a sensible run.