  A simple two charge system, one charge being suspended on a spring, exhibits
complex behavior including bistability, hysteresis and catastrophic response to
gradual variation of the external parameters. We discuss these complex features
(that can be related, e.g., to membrane electroporation and voltage gating of
ion channels) using only high school physics. Similar properties are displayed
by a system comprised of magnets and springs. Using this analogy, a simple
demonstration model was designed in collaboration with John Griffin, using
components of the "Rogers Connections" magnetic construction toy.
