# Doubt regarding Rutherford's Alpha Scattering Experiment and Impact Parameter

• B
• Bloopy
In summary, the conversation discusses the relationship between impact parameter and the scattering of alpha-particles. It is explained that if the impact parameter is large, the particles will be scattered through small angles due to the inverse relationship between the Coulomb force and distance. As the impact parameter increases, the force decreases, resulting in smaller scattering angles. This concept is further clarified in the conversation.
Bloopy
It is mentioned in my Textbook that if alpha-particle has large impact parameter, it gets scattered through small angles and vice versa.

I understand that impact parameter is defined as the perpendicular distance between the path of a projectile and the center of the nucleus.

I am unsure how the aforementioned fact is explained?

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How does the Coulomb (electric) force between the alpha-particle and nucleus vary with distance?

jtbell said:
How does the Coulomb (electric) force between the alpha-particle and nucleus vary with distance?
It is inversely proportional to the square of the distance between them.

So if the impact parameter becomes larger, what happens to the force?

jtbell said:
So if the impact parameter becomes larger, what happens to the force?
Force reduces drastically. Hence the scattering occurs through small angle. Understood.

jtbell

## 1. What was Rutherford's Alpha Scattering Experiment?

Rutherford's Alpha Scattering Experiment, also known as the Gold Foil Experiment, was a series of experiments conducted by physicist Ernest Rutherford in 1909 to study the structure of the atom. Rutherford bombarded a thin sheet of gold foil with positively charged alpha particles and observed the pattern of deflected particles to determine the structure of the atom.

## 2. What is the impact parameter in Rutherford's experiment?

The impact parameter in Rutherford's experiment is the distance between the path of the alpha particle and the nucleus of the atom it is interacting with. It is a measure of the closest approach of the alpha particle to the nucleus during the scattering process.

## 3. How did Rutherford's experiment challenge the prevailing atomic model at the time?

Rutherford's experiment challenged the prevailing atomic model, the Thomson atomic model, by showing that the atom is mostly empty space with a small, dense nucleus at its center. This contradicted the Thomson model, which proposed that the atom was a uniform sphere of positive charge with evenly distributed negative electrons.

## 4. How did Rutherford's experiment lead to the development of the nuclear model of the atom?

Rutherford's experiment led to the development of the nuclear model of the atom by providing evidence for the existence of a small, dense nucleus at the center of the atom. This led to further experiments and theories that eventually resulted in the modern understanding of the atom as containing a positively charged nucleus surrounded by negatively charged electrons.

## 5. What are some limitations of Rutherford's Alpha Scattering Experiment?

Some limitations of Rutherford's Alpha Scattering Experiment include the use of only one type of particle (alpha particles) and the assumption that the gold foil was uniformly thin. Additionally, the experiment did not account for the presence of neutrons in the nucleus, which were discovered later. Despite these limitations, Rutherford's experiment remains a significant milestone in the history of atomic research.

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