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Protons of energy 5.6 MeV are incident on a gold foil of thickness 3.9 x 10-6 m. What fraction of the incident protons is scattered at the following angles? (The density of gold is 19.3 g/cm3, and its molar mass is 197.0 g/mol. Give your answer in decimal notation, e.g., 0.05 for 1/20.) (a) greater than 90° 0.000074 (b) greater than 100 x (c) between 5° and 100 X (d) less than 50 x Additional Materials eBook

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Final answer:

The question relates to Rutherford's gold foil experiment and the scattering of protons. It demonstrates that atoms are mostly empty space with a dense nucleus, proven by a small fraction of particles, about 0.000074, being scattered at large angles. A detailed calculation of scattering at other angles would involve nuclear physics concepts and the Rutherford scattering formula.

Step-by-step explanation:

The question pertains to the scattering of protons when they hit a gold foil, which is an application of the famous Rutherford scattering experiment. In the provided context, Rutherford's experiment demonstrated that atoms consist of a small, dense nucleus surrounded by largely empty space, with the nucleus containing almost all of the atom's mass. This was concluded based on the unexpected deflection of alpha particles at large angles, which suggested that the alpha particles came very close to the dense positively charged nucleus, leading to a strong Coulomb force interaction.

The specific values mentioned (e.g., 5.6 MeV protons, gold foil thickness, etc.) are related to calculations to determine the fraction of particles scattered at various angles. Experiments like Rutherford's give insights into the structure of atoms, including the size of the nucleus and the distribution of its positive charge.

To address the student's question directly, the fraction of particles scattered above 90 degrees was observed to be about 0.000074, which is a very small fraction, reflecting the rarity of direct hits between the incident particles and the nuclei within the gold foil. Calculating the scattering at other angles would involve a complex understanding of nuclear interactions and is beyond the scope of a simple answer but could be estimated based on the experimental setup and the Rutherford scattering formula.

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User Ivan Buttinoni
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