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In Geiger-Marsden experiment, the number of scattered α-particles N(θ) is plotted as a function of scattering angle θ. Which of the following options represents the correct plot? (The four plots are shown in the figure, with N(θ) on a logarithmic scale.)

Asked in Re-NEET 2026 · Rutherford's model and its limits

• (1) Plot (1): N(θ) rises steadily as θ increases
• (2) Plot (2): N(θ) stays nearly level at small θ and then falls steeply towards 180°
• (3) Plot (3): N(θ) is largest at small θ and falls steadily, levelling off towards 180°
• (4) Plot (4): N(θ) is small at both ends with a flat maximum around 90°

Step-by-step solution

Why the other options are wrong

• (1) The count runs the other way: most α-particles pass almost undeflected, so small angles have by far the most.
• (2) The count does not stay level at small angles: 1/(sin⁴(θ/2)) falls fastest there.
• (4) There is no maximum at 90°; N(θ) falls monotonically from small angles to 180°.

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