To charge an electroscope negative using a positive rod
To charge an electroscope negative using a positive rod, you can follow these steps:
1. Rub the positive rod against a neutral material such as a piece of wool or silk to transfer some positive charge onto the rod.
2. Bring the positively charged rod close to the metal plate or cap of the electroscope while the electroscope is grounded (by touching the metal casing with your hand to allow charges to flow in and out).
3. The positive charges on the rod will induce an equal amount of negative charges on the metal plate or cap of the electroscope through electrostatic induction.
4. Remove the positive rod while keeping the electroscope grounded. The excess negative charges will remain on the metal plate or cap of the electroscope, giving it a negative charge.
5. Remove your hand from the metal casing of the electroscope to isolate it from the ground. The electroscope should now have a negative charge indicated by the divergence of the metal leaves inside.
By following these steps, you can charge an electroscope negative using a positive rod through the process of electrostatic induction.