It is a device used for detecting whether an object is charged or uncharged. It can also be used to determine the type of charge on a material.
The figure below shows the main features of a gold-leaf electroscope.
The cap, the stem, the plate and the leaf are made from conducting materials. Therefore any charge on the cap is easily transferred to the plate and leaf.
- The same kind of charge is transferred to the leaf and the plate. Therefore they repel each other and the leaf rises or diverges.
- When the leaf of the electroscope is up, it is said to be charged.
- Any charge on the metal casing that could induce charges on the leaf and the plate leaks to the earth.
One face of the casing is made of glass so that what is in the electroscope can be observed from outside.
CHARGING A GOLD-LEAF ELECTROSCOPE
There are principally two ways of charging the gold-leaf electroscope by contact and by induction.
- Charging the electroscope by contact
This simply involves rolling a charged rod continuously over the cap of the electroscope until the leaf rises significantly. Rubbing a charged polythene rod gives the electroscope a negative charge while rubbing a charged Perpex rod gives it a positive charge. It is not always easy to charge an electroscope by contact, most often the method of induction is used
- Charging the electroscope by induction
The figure below shows the steps involved in charging an electroscope by induction
Charging an electroscope positively involves similar steps but this time a negatively charged rod is used.
