PURPOSE: To demonstrate that inserting a dielectric into a parallel plate capacitor increases its capacitance.

DESCRIPTION: The parallel plate capacitor is charged by the power supply and the plates are separated, increasing the voltage between the plates (left picture). A thick dielectric sheet inserted between the plates of the capacitor results in a decrease in the voltage between the plates (right picture). Because the charge on the plates remained constant, this means that insertion of the dielectric has increased the capacitance. This allows more charge to be stored by the capacitor at the same voltage. Click your mouse on the photograph at the left to see it work.

SUGGESTIONS: See Question of the Week #110 for information on using this demonstration to enhance class involvement.

REFERENCES: (PIRA 5C20.10)

EQUIPMENT: Parallel plate capacitor setup with phenolic dielectric sheet.

SETUP TIME: None.