Immagini

DESCRIPTION

Exhibit 22 is a Kolbe electrometer, a precision form of gold-leaf electroscope. The instrument consists essentially of a conductor with attached gold leaf and a metal housing insulated from it through an insulating gasket. The potential difference exists between the conductor and the metal case that is often earthed. The conductor and the metal case constitute a capacitor with one of the two armatures movable. Such a capacitor does not have a simple shape, so it is not easy to calculate the deflection of the leaf as a function of the applied potential difference. In other words the electroscope necessarily needs to be calibrated for different applied voltages.

Roughly the leaf deflects by nearly 45° for a potential difference of 300 Volt. In excellent experimental conditions appreciable leaf deflections could be obtained corresponding to variations of ± 5V.

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