When a Silk cloth is rubbed with a glass rod, the rod :

Question

Accepted Answer

When a silk cloth is rubbed with a glass rod, the rod becomes positively charged while the cloth becomes negatively charged. This phenomenon can be explained through the concept of triboelectric charging, which involves the transfer of electrons between two materials when they are brought into contact and then separated.

1. **Explanation for Option 3:**
   - **Triboelectric Series:** The triboelectric series is a list that ranks materials based on their tendency to gain or lose electrons. In this series, glass is positioned higher than silk, indicating that glass has a greater tendency to lose electrons compared to silk.
   - **Electron Transfer:** When the glass rod is rubbed against the silk cloth, electrons are transferred from the glass to the silk. This transfer occurs because glass has a weaker hold on its electrons compared to silk.
   - **Charge Acquisition:** As a result of losing electrons, the glass rod becomes positively charged. Conversely, the silk cloth gains electrons and becomes negatively charged. This aligns with Option 3, which states that the rod becomes positively charged while the cloth is negatively charged.

2. **Explanation for Why Other Options are Incorrect:**
   - **Option 1:** This option suggests that both the rod and the cloth acquire a positive charge. This is incorrect because charge conservation dictates that if one object loses electrons and becomes positively charged, the other must gain those electrons and become negatively charged.
   - **Option 2:** This option states that both the rod and the cloth acquire a negative charge. This is not possible because the transfer of electrons results in one object gaining electrons (negative charge) and the other losing electrons (positive charge).
   - **Option 4:** This option claims that the rod becomes negatively charged while the cloth becomes positively charged. This contradicts the triboelectric series and the observed behavior of glass and silk, where glass tends to lose electrons and silk gains them.

In conclusion, the correct explanation supports Option 3, where the glass rod becomes positively charged and the silk cloth becomes negatively charged due to the transfer of electrons from the glass to the silk during the rubbing process.