Working of Electroscope

An electroscope is a simple device used to detect the presence and nature of electric charges. It consists of a metal rod, known as the stem, which is attached to a metal plate or leaf at the bottom. The stem is usually mounted inside a glass or plastic case to protect it from external disturbances.

Charging the Electroscope

To charge an electroscope, it needs to be brought in contact with a charged object. When a positively charged object is brought near the electroscope, it induces a separation of charges in the metal plate or leaf. The positive charges in the electroscope are attracted to the charged object, while the negative charges are repelled. As a result, the metal plate or leaf acquires a net positive charge.

Leaf Movement

The movement of the metal plate or leaf is a key indicator of the presence and nature of electric charges. When a charged object is brought near the electroscope, the metal plate or leaf is repelled or attracted, causing it to move.

Positive Charge

If the metal plate or leaf repels, it indicates the presence of a like charge. For example, if a positively charged object is brought near the electroscope, the metal plate or leaf, which is already positively charged, will repel further.

Negative Charge

If the metal plate or leaf is attracted, it indicates the presence of an opposite charge. For instance, if a negatively charged object is brought near the electroscope, the metal plate or leaf, which is initially positively charged, will be attracted towards the negatively charged object.

Neutral Charge

If the metal plate or leaf remains unaffected and does not show any movement, it suggests that the object is electrically neutral, meaning it has an equal number of positive and negative charges.

Discharging

To discharge an electroscope, it can be touched with a conductor, such as a metal wire, which allows the charges to flow through it and neutralize the electroscope. This brings the metal plate or leaf back to its original neutral state.

In summary, an electroscope works by detecting the movement of a metal plate or leaf in response to the presence of electric charges. It can determine the nature of the charges (positive or negative) based on the direction of the movement (repulsion or attraction). Discharging the electroscope restores it to a neutral state.