9. Explain construction and working of electroscope.

An electroscope is a simple device used to detect the presence and magnitude of electric charges. It operates based on the principle of electrostatic induction and the repulsion of like charges.

Here's how a basic electroscope works and its construction:

Construction:

1. Metal Leaf: The main component of an electroscope is a metal leaf, typically made of a lightweight metal such as aluminum or gold. The metal leaf is usually attached to a metal rod or wire, which is insulated from the surroundings by a non-conductive material, such as plastic or glass.

2. Support Structure: The metal rod holding the metal leaf is mounted vertically within a non-conductive container, such as a glass jar or case, to protect it from external influences.

3. Leaf Suspension: The metal leaf is suspended from the metal rod at its upper end, allowing it to move freely in response to electric charges.

Working:

1. Charging: To use the electroscope, it must first be charged. This can be done by bringing a charged object (such as a rubbed glass rod or a plastic comb) near the metal rod of the electroscope without touching it. The charged object induces a separation of charges in the metal leaf, causing like charges to be repelled and move away from the metal rod.

2. Leaf Movement: As the like charges in the metal leaf repel each other, the metal leaf diverges from the metal rod, moving outward to a certain extent. The degree of divergence depends on the magnitude of the charge induced on the metal leaf.

3. Observation: The divergence of the metal leaf is visually observed through a transparent window or opening in the container housing the electroscope. The greater the divergence of the metal leaf, the larger the magnitude of the electric charge present.

4. Discharging: Once the charged object is removed, the electroscope gradually discharges due to the movement of charges within the metal leaf. The metal leaf returns to its original position, indicating that the electric charge has dissipated.

Overall, an electroscope detects the presence of electric charges by observing the movement of a metal leaf in response to electrostatic forces. It is a simple yet effective tool for demonstrating the principles of electrostatics and for detecting the presence of electric charges in various objects and materials.