Editing Photoelectric Effect (section)

== Why This Works ==

The ''Photoelectric Effect'' is the phenomenon when a photon with sufficiently high energy can strike an electron and free it, resulting in an electric charge. When Einstein introduced this idea, he was the first to suggest the idea of a ''Photon'', which is a light wave behaving like a particle. Einstein suggested that a light wave of sufficiently high energy could strike an electron on a metal surface and free it, and that for this to happen the light wave would have to act similarly to a particle. He built this idea off of the work of Max Planck, who developed this formula for the energy of an emitted electron:

{| class="wikitable" style="color:black; background-color:#ddd; text-align: left; margin-right: auto"
| '''K'''<sub>max</sub> = '''ħ'''(''f'' - ''f''<sub>0</sub>)
|-
| '''K'''<sub>max</sub>: Max Kinetic Energy for emitted electron
|-
| ''f'': Frequency of incoming light
|-
| ''f''<sub>0</sub>: Minimum frequency of light needed
|-
| '''ħ''': Planck Constant = ''h''/2(pi)
|}

For this equation, the incoming light needs to be at a higher frequency than what is needed to free the electron. If it isn't, then the equation would give a negative value, which means that nothing would happen. From this to happen, Einstein proposed that the light waves would have to act like particles. He called these light particles ''Photons'', and proposed that only the higher energy photons would be able to strike an electron and free it, while low energy photons would be unable to do so. What made this idea revolutionary is that it is unaffected by the ''Intensity'' of the light, or how bright the light is, and only affected by the ''Wavelength'', or color of the light.

Our circuit setup has electrons ready to jump across the gap in the bulb, but they don't have enough energy to do so. By using the flashlight, one can show how the color of the light affects it, while the brightness of the light, which stays the same for both colors, does not. The red photons have a longer wavelength, and therefore a lower frequency, which is why they cannot trigger the circuit. The blue photons have a shorter wavelength, and therefore a higher frequency, which is why they can trigger the circuit!