Photoelectric Effect

What is the photoelectric effect?
- The photoelectric effect is a phenomena that occurs when 
photons emit electron off of a surface which is being struck
by light. (As the photo below shows.)

How is it used?
- The photoelectric effect is used with automatic doors, when
you walk towards the doors. There are pho-todectors that have
a beam of light shining on it and when you approach the doors,
you are ceasing the electrons in the pho-todectors and allowing 
the doors to open.

Does it use light as a particle, a wave, or both?
- Particles. Einstein proposed that light delivers in chunks, particles.
Because frequency makes a difference in the photoelectric effect,
waves would not fit into how it is used. Quanta called photons 
move at a quicker speed because of the difference in frequency
emitting electrons faster.