Versorium

The versorium represents one of the first modern electrical measuring instruments dar. It is a very simple design an electroscope and serves as a rough determination of the electrostatic field distribution. It is mechanically similar to a compass needle, but is, in contrast, not of a magnetic needle, but reacts by deflecting a metallic needle on the static electric field. It is thus possible to distinguish close to a body, whether it is static electrically charged or not.

Was constructed the versorium around 1600 by the English physician and physicist William Gilbert, after he had occupied himself with the writings of the Italian physician Girolamo Fracastoro.

Construction

The versorium consists of a thin, non-magnetic needle, designed like a compass needle, which is stored centrally and can easily rotate around the support point. Due to the force acting on electric charges it comes to induction, ie for the displacement of electric charges in the metallic needle. Because of the electrical forces, such as expressing the Coulomb's law, it is thus in the presence of electrostatically charged bodies in a rotational movement of the needle towards the electrostatically charged body. For electrically uncharged bodies in the vicinity there is no force acting on the needle and it remains in the existing position.

The symmetry of the charge displacements in the needle makes both ends of the needle as a pointer usable. A distinction between a positive or negative electrically charged objects is not possible with this arrangement.

Due to the simple and intuitive design of structures are similar to the versorium used in school physics classes as an experimental and craft object.

Magnetic versorium

William Gilbert describes in his original work also has a similar structure in the so-called magnetic versorium whose needle is made of a hard magnetic material and is identical to the function of a compass needle. The compass needle or the magnetic versorium aligns itself with an external magnetic field.

Importance

By using the non-magnetic and magnetic Versoriums Gilbert difference in his work unique and one of the first between the effects of magnetism and the effects of electrostatics.