The capacitor investigation provides a self-contained unit to enable students to study the charge and discharge characteristics of a capacitor. The large value of C (0.01F) and the resistor chosen give a time constant of about 50 seconds so that students can easily take a manual set of readings for plotting a graph. Data-logging equipment can just as easily be used and if a faster response is required a parallel resistor could be plugged in. Connections are by standard 4mm plugs and analogue or digital meters are suitable.