Figure 22.8 showed how an electroscope becomes negatively charged. The leaves will also repel each other if you touch the electroscope with a positively charged glass rod. Use a series of charge diagrams to explain what happens and why the leaves repel each other.

Verified step by step guidance

1. Identify the initial state of the electroscope: Before touching it with the positively charged glass rod, the electroscope is neutral, meaning it has an equal number of protons (positive charges) and electrons (negative charges).
2. Understand the effect of the positively charged glass rod: When the positively charged glass rod comes into contact with the electroscope, it attracts the free electrons in the metal of the electroscope towards the top where the contact is made.
3. Recognize the redistribution of charge: As electrons move towards the top, the lower part of the electroscope becomes deficient in electrons and thus relatively positively charged.
4. Explain the repulsion of the leaves: Since the leaves of the electroscope are now both positively charged due to the deficiency of electrons, they repel each other because like charges repel according to Coulomb's Law.
5. Visualize the final state: The leaves stay apart as long as the imbalance of charge is maintained. Removing the glass rod or grounding the electroscope would allow the charges to redistribute evenly, returning the leaves to their uncharged, non-repelled state.

Key Concepts

Electrostatic Charge

Electrostatic charge refers to the physical property of matter that causes it to experience a force when placed in an electromagnetic field. Objects can be positively charged, negatively charged, or neutral, depending on the balance of protons and electrons. When a charged object comes into contact with a neutral object, it can transfer charge, leading to the phenomenon of attraction or repulsion between the objects.

Electroscope Functionality

An electroscope is a device used to detect electric charge. It consists of a metal rod connected to two thin metal leaves. When the electroscope is charged, the leaves acquire the same type of charge, causing them to repel each other due to the electrostatic force. This repulsion is a clear indicator of the presence of charge in the electroscope.

Charge Induction

Charge induction is the process by which a charged object can cause a redistribution of charges in a nearby neutral object without direct contact. When a positively charged glass rod is brought near the electroscope, it attracts electrons from the leaves, causing them to become negatively charged. This results in both leaves having the same negative charge, leading to their repulsion from each other.