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.