SAT Subject Physics Practice Question 447: Answer and Explanation

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Question: 447

8. The drawing represents the results in a Young's double slit interference pattern experiment.

What does the photoelectric effect demonstrate?

A. The particulate nature of light
B. The wave nature of light
C. The diffuse reflection of light
D. The total internal reflection of light
E. The polarization of light

Correct Answer: A


The correct answer is (A). The wave nature of light does not satisfactorily explain why low frequency light cannot energize electrons from the surface of metals, which high frequency light does. The intensity of the light doesn't matter. This is explained by the particle theory in which photons carry energy, which is transferred to electrons in the metal.

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