Question:

In the Geiger-Marsden experiment, the number of scattered \(\alpha\)-particles \(N(\theta)\) is plotted as a function of scattering angle \(\theta\). Which of the following options represents the correct plot?

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Rutherford scattering predicts that most alpha particles suffer very small deflections and only a few are scattered through large angles.
Updated On: Jun 21, 2026
  • Graph (1)
  • Graph (2)
  • Graph (3)
  • Graph (4)
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The Correct Option is D

Solution and Explanation

Concept:

• Rutherford scattering law states: \[ N(\theta)\propto \frac{1}{\sin^4(\theta/2)} \]

• Most \(\alpha\)-particles are scattered through small angles.

• Very few particles are scattered through large angles.

Step 1: Examine the scattering formula.
\[ N(\theta)\propto \frac{1}{\sin^4(\theta/2)} \] As \(\theta\) increases, \(\sin(\theta/2)\) increases. Therefore \(N(\theta)\) decreases rapidly.

Step 2: Analyze the nature of the graph.
At very small angles, \[ N(\theta) \] is extremely large. At larger angles, \[ N(\theta) \] falls sharply toward zero. This corresponds to Graph (4). \[ \boxed{\text{Option (D)}} \]
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