J4-01. Parallel Plate Capacitor

Purpose

To demonstrate that the voltage across a capacitor is proportional to the plate separation.

Equipment

Parallel plate capacitor assembly with electrometer as photographed.

Images

Description

The parallel plate capacitor is charged to 1200 Volts using a chain of 300 Volt batteries, and the battery lead removed. (A series resistor limits the current from the batteries.) The plates may then be separated and the voltage observed using the electrometer, demonstrating that the voltage is proportional to the plate separation.

References

Herbert H. Gottlieb, Variable Capacitor, TPT 5, 86, (1967). ◙F. N. Yan and H. K. Wong, Force between the plates of a parallel-plate capacitor, AJP 61, 1153 (1993).