Rc Circuit - Rc Time Constant - Oscilloscope


To measure an RC time constant and to observe the shape of the charging and discharging curves.


RC circuit with meters on plastic sheet for overhead projector use, 30 and 100 microfarad capacitors, 5 and 10 kilohm resistors, overhead projector, oscilloscope on scope/TV cart.


Setup Time

5 min.




    An RC circuit with meters is mounted on an overhead projector projectual. The voltage across the capacitor and the charging current are displayed. Either the voltage across the capacitor or the charging current (voltage across the series resistor) can also be displayed on the oscilloscope. Various combinations of resistance and capacitance can be plugged into the circuit. See circuit diagram below.◙


    J. Gordon Stipe, Transient Currents in Switched DC Circuits, Novel Experiments in Physics II. ◙Robert A. Egler and William M. Mauney, Capacitor Current-Voltage Phase Difference, TPT 29, 398 (1991). I. Fundaun, C. Reese, and H. H. Soonpaa, Charging a capacitor, AJP 60, 1047-1048 (1992).