SAT Subject Physics Practice Question 195: Answer and Explanation

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Question: 195

41. What did Rutherford’s experiments on alpha particle scattering indicate about the structure of the atom?

A. Atoms are roughly spherical with a radius of about 10–10 m.
B. The electrons occupy quantized energy levels, absorbing or emitting energy only when they make a quantum jump between these levels.
C. The density of positive charge within an atom is not uniform throughout the atom’s volume.
D. Allowed electron orbits must have a circumference equal to a whole number times the electron’s de Broglie wavelength.
E. Alpha particles are positively charged.

Correct Answer: C


A and E were known before Rutherford conducted this series of experiments, and B and D concerning the electrons were proposed later by Bohr. What Rutherford discovered with these experiments was that an atom’s positive charge was not uniformly distributed throughout the entire atom but was instead concentrated into a very small volume at the atom’s center (the nucleus).

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