Image provided by NetNano

Energy Level and Infinite Square Well 

    The idea of an "energy level" is if a particle is quantized then all of the properties of that particle is quantized including energy.  The infinite square well is a way to show these energy levels.  

    Why does it have to be infinite?  Well the idea is that wave cannot make it beyond the "walls" of the "well", the infinite square well means it would take an infinite amount of energy to penetrate the walls

The red curve is the ground energy level 

The dark purple line is fifth energy level. 

With the a higher energy level, the wavelength is reduced by a 1/2  (remember the higher frequency means higher energy)