Question

Draw the graph showing the variation of number of scattered alpha particles (N) detected with scattering angle (θ) in Geiger-Marsden experiment. Infer two conclusions from the graph.

Answer 1

The graph plots the number of scattered α-particles (N) on the Y-axis (often on a log scale) against the scattering angle (θ) on the X-axis.

The graph shows a very high count for small angles (θ < 1°) and drops exponentially as θ increases, with very few particles scattered at angles near 180°.

Two conclusions from the graph:

1. Most of the atom is empty space: It is implied that the majority of the atom’s volume is empty because the great majority of α-particles passed through the gold foil with little to no deflection (small θ).
2. The nucleus is small and positively charged: The percentage of α-particles that were deflected by more than 90° was quite small, approximately 1 in 8000. This suggests that an incredibly tiny, compact area known as the nucleus contains the atom’s positive charge and almost all of its mass.