MCAT Physics Question 126: Answer and Explanation

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Question: 126

6. Ultraviolet light is more likely to induce a current in a metal than visible light. This is because photons of ultraviolet light:

  • A. have a longer wavelength.
  • B. have a higher velocity.
  • C. are not visible.
  • D. have a higher energy.

Correct Answer: D

Explanation:

The photoelectric effect occurs when a photon of sufficiently high energy strikes an atom with a sufficiently low work function. This means that a photon with higher energy is more likely to produce the effect. Because ultraviolet light has a higher frequency and lower wavelength than visible light, it also carries more energy according to the equation E = hf. All light travels at the speed of light, eliminating choice (B). As mentioned earlier, ultraviolet light has a shorter wavelength than visible light, eliminating choice (A). The visibility of a wave plays no role in its ability to cause the photoelectric effect, eliminating choice (C).

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