Question

You are provided with a negatively charged gold leaf electroscope. What is the effect on the gold leaves when a glass rod rubbed with silk is brought near the disc of electroscope?

• A. Divergence increases
• B. Divergence decreases
• C. Divergence remains same
• D. Can not be determined

Answer 1

The correct option is B Divergence decreases

On rubbing a glass rod with silk, the electrons from the glass rod get transferred to the silk. The silk now has an excess of electrons and so is negatively-charged. On the other hand, the glass rod is deficient in electrons and hence is positively-charged.
In the above case, the silk undergoes negative electrification.
Now, when the positively charged glass rod is touched on the disc of a negatively charged gold leaf electroscope, the electrons shifts towards rod, hence amount of charge on gold leaves decreases and the divergence between the gold leaves decreases as unlike charges attract each other.
Hence, the divergence decreases when a glass rod rubbed with silk is brought near the disc of negatively charged electroscope.