Practice question · Select all that apply
Which observations are explained by treating light as photons rather than as a continuous wave?
Hints
- Three need energy to arrive in indivisible packets; one is classical wave behaviour.
- Refraction is explained perfectly well by the wave picture alone.
Show the answer
- A. Instantaneous ejection of electrons at very low intensity
- B. Emission of sharp spectral lines from a heated gas
- D. A threshold frequency for the photoelectric effect
Why
The frequency threshold, sharp line spectra and immediate ejection at low intensity all demand quantised energy packets. Refraction is pure wave behaviour and never needed photons.
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