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In Geiger-Marsden scattering experiment the thickness of a thin foil of gold is ________ m.

Asked in GUJCET 2024 · Rutherford's model and its limits

• (1) 5.5 × 10⁻⁷
• (2) 4.2 × 10⁻⁷
• (3) 2.1 × 10⁻⁷
• (4) 6.2 × 10⁻⁷

Step-by-step solution

Why the other options are wrong

• (1) 5.5×10⁻⁷ m is about 2.6 times the thickness Geiger and Marsden used; the thicker the foil, the more likely an α-particle is to be deflected twice on the way through, and Rutherford's formula assumes that it is not.
• (2) 4.2×10⁻⁷ m is exactly twice the real thickness 2.1×10⁻⁷ m — the right digits, doubled.
• (4) 6.2×10⁻⁷ m is nearly three times the thickness actually used, and no step of the experiment produces it. The foil was 2.1×10⁻⁷ m thick, about 0.21 μm.

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