Exam-style question
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Which experiment provided the first clear evidence that light behaves as a particle?.
- A.Young’s double‑slit experiment
- B.The photoelectric effect
- C.Diffraction of X‑rays
- D.The Michelson–Morley experiment
Model answer
What a good answer should say
- The photoelectric effect showed light acts as particles.
Explanation
Why this works
The photoelectric effect demonstrated that light of sufficient frequency ejects electrons instantaneously, a behaviour that cannot be explained by a purely wave model. This was the first clear evidence of light’s particle nature.
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