Periodic Potential

atomic lattice - potential wells - equilibrium positions

What it shows:
Ball bearings simulate atoms in a lattice sitting at local potential minimums. Giving them energy excites the atoms and they oscillate about their equilibrium positions in these wells; only with large amounts of energy can they be truly dislocated.

How it works:
A piece of wood 100 x 25 x 2cm acts as the ‘potential’ structure of the lattice. The atoms, 3cm diameter ball bearings sit at the bottom of a cosine varying potential cut to about 10cm depth in the wood by a jig saw.The balls are held in the 2-dimensional wells by plexiglass shields on either side of the wood with a spacing of 3.5cm. The assembly is mounted on a dynamics cart. You can then impart energy to your lattice by vigorous rolling back and forth.

figure 1.the potential well shaker

Comments:
Simple and stylized, it makes the point. Instead of a dynamics cart, a piece of 2x4 with wheels will suffice (smooth running is not a necessity). Rating**