Understanding Electron Liberation in Relation to Light Frequencies

[member 529879]

In my physics class we are learning about certain frequencies of light hitting and "liberating" electrons, but we didn't go into any detail about what "liberating" the electron means. Can somebody explain?

 

[robphy]

Here's a place to start:
http://en.wikipedia.org/wiki/Photoelectric_effect
https://phet.colorado.edu/en/simulation/photoelectric

Liberating is "being freed" from being bound to the metal surface.