Electroscopio

The first electroscope was a device called a versorium, developed in 1600 by William Gilbert a physician to Queen Elisabeth I.. The versorium was simply a metal needle allowed to pivot freely on apedestal. The metal would be attracted to charged objects brought near.
An electroscope is an instrument used to determine if a body is electrified, and to determine the nature of the electrification.An electrometer, on the other hand, is a specialized form of electroscope that includes a calibrated scale for reading the strength of the charge.
The first true electrometer came from HoraceBenedict de Saussure (1740-1799) who placed the strings and balls inside an inverted glass jar and added a printed scale so that the distance or angle between the balls could be measured. It was de Saussurewho discovered the distance between the balls was not linearly related to the amount of charge. Abraham Bennet discovered that gold foil was much more sensitive than cork or pith and created thefirst gold leaf electroscope in 1786.
An electroscope is used by physics teachers to illustrate electrostatic principles of charging and charge interactions. The electroscope is most commonly used as acharge-detecting device. It consists of two thin metal leaves suspended from a metal hook. When the hook is brought near a source of static electricity, some of the electrons in the hook are pushedto the leaves (if the source is negative) or pulled up to the hook from the leaves (if the source is positive). Either way, the leaves are now charged the same way as each other and so they repel eachother. The amount they open up is proportional to the charge of the source (if the sources are always held at the same distance from the hook).
Rubbing a plastic ruler with cloth would cause bothobjects to be charged eletrostatically. Electrostatic forces of attraction between positive and negative charges on both objects would cause a movement, or a transfer of electrons between the objects,...