The condenser electroscope permits experimental study of the capacity of the condenser as a function of its geometrical characteristics.

This apparatus consists of a gold-leaf electroscope in electrical contact with a horizontal disc attached to the upper end of the electroscope's shaft. This disc is in contact with a second disc fixed vertically in front of a third one, also vertical, parallel to the second and mounted on a movable brass rod. The distance between the two vertical discs can be regulated by sliding the support of the movable disc along a groove on the wooden base of the device.

When the electroscope disc is connected to the ground, and the movable disc to an electrostatic machine, the gold leaves in the electroscope repel one another. This phenomenon results from the distribution of the charge created by the influence of the movable disc. In these conditions, when the movable disc is brought nearer to the fixed disc, the gold leaves in the electroscope repel one another more strongly, indicating an increase in electrical charge on the vertical disc connected to the electroscope. This experiment leads to the conclusion that the electrical charge distributed on the condenser shield depends on the distance between its shields.

When the ground lead is disconnected, once the electroscope is charged, the gold leaves do not change their position significantly when the movable shield is brought nearer to, or removed from the electroscope. This means that the electrical charge of the electroscope is unchanged. But if the movable shield of the condenser is subsequently disconnected from the electrostatic machine, and then the electrical contact between the two shields is established, the gold leaves move closer together and the electroscope is discharged. This experiment leads to the conclusion that the shields of the condenser are symmetrically charged when it is connected between an electrostatic machine and the ground.