HW Question 1B.3

[Jessica Esparza 2H]

The answer to the following question is The Photoelectric effect but I am having trouble understanding why. Could someone please explain?

From the following list of observations, select the one that best supports the idea that electromagnetic radiation has the properties of particles. Explain your reasoning.
a) Black-body radiation
b) Electron diffraction
c) Atomic spectra
d) The photoelectric effect."

[Kurtis Liang 3I]

According to the photoelectric effect, light sources with long wavelengths cannot eject electrons, even if they have high intensity. This explains the idea that light acts as a series of packets.

[Christine Honda 2I]

In the photoelectric experiment, a certain light was used to attempt to eject an electron from a metal. The experiment showed that if the light were a wave, then simply increasing the intensity would increase energy. But, increasing the intensity of the light did not result in ejection. Scientists then tried changing the type of light to a lower wavelength which worked to eject an electron from metal, this proved that light has particle properties. The increase in intensity just increases the number of particles and so you actually need the right energy instead of intensity.