Versorium
The Versorium is one of the first modern electrical measuring devices . It is a very simple design of an electroscope and is used to roughly determine the electrostatic field distribution. It has a similar mechanical structure to a compass needle , but in contrast does not consist of a magnetic needle, but reacts to the static electrical field by deflecting a metallic needle . It is thus possible to differentiate close to a body whether it is statically charged or not.
The Versorium was constructed around 1600 by the English doctor and physicist William Gilbert , after studying the writings of the Italian doctor Girolamo Fracastoro .
construction
The Versorium consists of a thin, non-magnetic needle, designed similarly to a compass needle, which is mounted centrally and can rotate very easily around the point of support. The effect of the force on electrical charges leads to influence , i.e. a shift in the electrical charges in the metallic needle. Due to the electrical forces, as expressed by Coulomb's law , when electrostatically charged bodies are present, the needle rotates in the direction of the electrostatically charged body. In the case of electrically uncharged bodies in the immediate vicinity, there is no force on the needle and it remains in its existing position.
The symmetry of the charge displacements in the needle makes both needle ends usable as pointers. A distinction between electrically positive and negative charged bodies is not possible with this arrangement.
Because of the simple and clear design, structures similar to the Versorium are used in school physics lessons as objects for experimentation and handicrafts.
Magnetic Versorium
In his original work, William Gilbert also describes a so-called magnetic versorium with a similar structure, the needle of which 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 .
meaning
Through the use of the non-magnetic and the magnetic versorium, Gilbert differentiated clearly and as one of the first between the effects of magnetism and the effects of electrostatics in his work .
literature
- William Gilbert : De magnets, magneticisque corporibus, et de magno magnets tellure . Petrus Short, London 1600 ( online at Google Books - facsimile of the first Latin edition, Mayer & Müller, Berlin 1892).
- William Gilbert: On the magnet, magnetick bodies also, and on the great magnet the earth . Chiswick Press, London 1900 ( online at Projekt Gutenberg - English translation).
Individual evidence
- ↑ Andre Koch Torres Assis (Ed.): The Experimental and Historical Foundations of Electricity . 1st edition. C. Roy Keys, 2010, ISBN 978-0-9864926-3-1 , chap. 3 , p. 33–58 ( online (PDF; 4.6 MB)).
- ↑ Gilbert's Versorium . In: Resources for science learning . The Franklin Institute. Archived from the original on April 25, 2012. Retrieved September 27, 2013.