Place your hands on the side of your head, with your palms facing forward. This should look like you have given yourself large ears. Now completely rotate the Earth (your head) relative to the Sun (the light). What did you just model?

Materials will have different energies associated with the electrons inside them. this is related to how strongly bound they are by their work function. if we sandwich a material with a very low energy between two materials with a high energy, we create a trap for an electron. if this trap is very narrow in one direction in comparison to the others, this is approximately a 1-dimensional box that confines the electron. what is the lowest energy of an electron in the box if the thinnest direction across the materials is 4.81 nm?