Physics (AS & A Level) · Feb / March 2022 · Paper 12 · Question 38

When α-particles are directed at gold leaf: 1 almost all α-particles pass through without deflection 2 a few α-particles are deviated through large angles. What are the reasons for these effects?

1. Amost α-particles have enough energy to pass right through the gold leaf | gold is very dense so a few low energy α-particles bounce back from the gold surface
2. Bmost α-particles miss all gold atoms | a few α-particles bounce off gold atoms
3. Cthe gold nucleus is very small so most α-particles miss all nuclei | occasionally the path of an α-particle is close to a nucleus
4. Dthe positive charge in an atom is not concentrated enough to deflect an α-particle | occasionally an α-particle experiences many small deflections in the same direction

As printed in the paper