Wavelike/particle-like properties

[VZX]

How does the photoelectric effect experiment show particle-like properties while the black-body radiation, electron diffraction, and atomic spectra show wavelike properties of EM radiation?

[Miranda Hess 3I]

I think the reason that it was different for the photoelectric effect was that you wouldn't get a discrete threshold energy with wave-like properties. Looking at the light from the perspective of photons as individual particles, we can see a certain, discrete amount of energy hitting the surface and either hitting the threshold ejection energy or not.

[805812306]

The most helpful explanation for me was pointing out that increasing the intensity of the light did not increase the number of particles ejected from the metal surface. Under the wave explanation of photons, increasing the intensity would certainly increase the energy of the wave, which was not experimentally supported by the photoelectric effect.