EFFECT OF SPACING AND DIELECTRIC
ON A CAPACITOR

EQUIPMENT
    Parallel Plates
    Electroscope
    Rubber Rod and Fur
    Glass Rod and Silk
    Dielectrics (Mica, Glass, Plexiglas, Al)



NARRATIVE
            The capacitance of a parallel plate capacitor is inversely proportional to the distance between the plates and dependent on the material between the plates.  Connect the movable plate to the frame of the electroscope.  Connect the other plate to the top jack of the electroscope. Separate the plates and charge the stationary plate with the rubber rod and fur until the deflection is noticeable.  Bring the plates closer and deflection decreases.   Move the plates apart and the deflection returns. Insert one of the sheets of Mica, Glass, Plexiglas, or Aluminum between the plates.  Do not touch the plates or discharge will occur.  The deflection should decrease slightly.  Remove the dielectric and the deflection returns.

Works well only on a very dry day.