Periodic Potential

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 × 25 × 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

periodic potential


Simple and stylized, it makes the point. Instead of a dynamics cart, a piece of 2×4 with wheels will suffice (smooth running is not a necessity).