`alpha`- particles are incident on a thin gold foil. For what angle of deviation will the number of deflected `alpha`-particles be minimum ?

Explanation

To determine the angle of deviation at which the number of deflected alpha particles is minimum when they are incident on a thin gold foil, we can analyze the situation based on Rutherford's scattering experiment.

### Step-by-Step Solution:

1. **Understanding Alpha Particle Scattering**:
- Alpha particles are positively charged particles that are emitted from radioactive materials. When they are directed towards a thin foil of gold, they interact with the nuclei of the gold atoms.

2. **Rutherford's Experiment**:
...