1.21 [ENDORSED]

[KateCaldwell 1A]

"From the following list of observations, select the one that best supports the idea that electromagnetic radiation has the properties of particles. Explain your reason."

Can someone further explain the reasoning behind Einstein's theory of the photoelectric effect? Is he insisting that photons act like particles?

[Joshua Yang 1H]

Just writing what I have on my notes

Key Concept: If EMR only had wave properties, then increasing the intensity of the EMR should theoretically eject electron

However according to the experiment...
Light sources with long wavelengths cannot eject electrons. BUT light sources with short wavelengths can eject electrons

* Increasing EMR intensity means increasing the number of photons. However, the number of photons doesn't matter as to whether or not the electron is ejected. Rather, the energy contained within each photon (frequency) is what determines whether or not the electron is emitted

Therefore, we can determine that 1 electron interacts with 1 photon. Like particles.

[Cade Okohira 4K]

I said that the photoelectric effect best supports this idea because in this experiment, a certain light was used to try to eject an electron from a metal. Increasing the intensity was thought to increase the energy, but this did not work. Only changing the type of light to a lower wavelength worked. So, light has particle properties because the right type of energy is needed before intensity becomes a factor.