A simple ‘hands on’ physical model is described which displays analogous behaviour to some aspects
of the free electron theory of metals. Using it students can get a real feel for what is going on
inside a metallic conductor. Ohms Law, the temperature dependence of resistivity, the dependence of
resistance on geometry, how the conduction electrons respond to a potential difference and the
concepts of mean free path and drift speed of the conduction electrons can all be explored. Some
quantitative results obtained by using the model are compared with the predictions of Drude’s free
electron theory of electrical conduction.