Exam-style question
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Why does increasing the intensity of light above the threshold frequency not increase the kinetic energy of emitted electrons?.
- A.Because higher intensity reduces the work function of the metal.
- B.Because each photon still carries the same energy hf, independent of intensity.
- C.Because the electrons are limited by the metal’s temperature.
- D.Because the intensity only affects the number of photons, not their energy.
Model answer
What a good answer should say
- Because each photon still carries the same energy hf, independent of intensity.
Explanation
Why this works
Intensity changes the number of photons per unit time, not the energy per photon. Thus kinetic energy depends only on frequency, not intensity, in line with photon theory.
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