When a glass rod is rubbed with a piece of silk cloth the rod

Options

A. and the cloth both acquire positive charge.
B. becomes positively charged while the cloth has a negative charge.
C. and the cloth both acquire negative charge.
D. becomes negatively charged while the cloth has a positive charge.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks what happens when a glass rod is rubbed with a piece of silk cloth. We need to determine the charges acquired by both the glass rod and the silk cloth.

2. **Concept of Charging by Friction**: When two different materials are rubbed against each other, they can transfer electrons. This process is known as charging by friction. The material that loses electrons becomes positively charged, while the material that gains electrons becomes negatively charged.

3. **Identifying the Materials**: In this case, we have a glass rod and a silk cloth. It is important to know the electron affinity of both materials to predict which one will gain or lose electrons.

4. **Electron Affinity**: Glass has a lower electron affinity compared to silk. This means that when the glass rod is rubbed with the silk cloth, the glass rod will lose electrons and become positively charged, while the silk cloth will gain those electrons and become negatively charged.

5. **Conclusion**: After rubbing the glass rod with the silk cloth, the glass rod acquires a positive charge, and the silk cloth acquires a negative charge. Therefore, the correct answer is that the glass rod becomes positively charged while the silk cloth becomes negatively charged.

**Final Answer**: The glass rod becomes positively charged while the silk cloth has a negative charge (Option 2).

---