Question

In the Rutherford’s alpha scattering experiment, as the impact parameter increases, the scattering angle of the alpha particle

• A. is always 90°
• B. decrease
• C. increases
• D. remains the same

Answer 1

The Correct Option is B

Step 1: Understanding Rutherford’s Alpha Scattering Experiment 
In Rutherford’s alpha scattering experiment, the impact parameter (\( b \)) is defined as the perpendicular distance between the direction of motion of the alpha particle and the center of the nucleus of the atom being targeted.

Step 2: Relation between Impact Parameter and Scattering Angle
The scattering angle (\( \theta \)) is the angle through which the alpha particle deviates from its original path. As per Rutherford’s scattering theory:

• A small impact parameter (alpha particle approaching nucleus closely) leads to a large scattering angle (close to 180° for a head-on collision).
• A large impact parameter (alpha particle passing far away from nucleus) leads to a smaller scattering angle (particle barely deflected).

Thus, clearly as the impact parameter increases, the scattering angle decreases.

Answer 2

In Rutherford's alpha scattering experiment, the scattering angle of the alpha particle depends on the impact parameter. The impact parameter is the perpendicular distance from the center of the target nucleus to the trajectory of the alpha particle.

As the impact parameter increases, the distance between the alpha particle and the nucleus also increases, meaning the force of interaction becomes weaker. This results in a smaller scattering angle. Therefore, as the impact parameter increases, the scattering angle of the alpha particle decreases.

Thus, the correct answer is that the scattering angle decreases as the impact parameter increases.