Question

When a glass rod is rubbed with silk
A.) Negative charge is produced on silk but not charge on the glass rod
B.) Equal but opposite charge are produced on the both
C.) Equal and similar charges are produced on the both
D.) Positive charge is produced on the glass rod but no charge on the silk.

Answer 1

Hint: Silk and glass rod are electrostatic materials. When they are rubbed against each other, static electricity can be created. The rubbing makes negative charge that is carried by electrons. These electrons are the reason behind the static electricity. Thus, silk will be negative while glass rods will be positive due to the electron transfer between them.

Complete step by step answer:
When a glass rod is rubbing with fur, the electrons from the glass get transferred to the silk. Hence the glass rod behaves like a positively charged due to the deficiency of electrons and silk behaves like a negatively-charged due to the excess of electrons. Moreover, the electrons in the outermost orbit of the glass rod are loosely bounded. Hence, it will be easy to transfer electrons from a glass rod to silk. Friction between the two materials makes the material either electron-deficient or electron excess. This is a form of triboelectric effect. Due to this phenomena, silk and glass rods will attract each other. This electrostatic charge accumulation makes them attractive.

That means equal but opposite charges are produced on both materials So, the answer is option B.

Additional information: Why do the electrons not go from silk to glass? It depends on the material properties. For any two-material system, one of them will be electron loving. For a glass-silk system, electrons are more comfortable with a silk cloth.

With this positively charged glass rod we can attract uncharged paper pieces. It is not only because of the accumulation of a particular charge. According to our atomic concepts, only electrons can move around. So only glass rods can induce the net negative charge at the edge of the paper pieces. Otherwise, the negatively charged silk can also attract paper pieces, since paper pieces are neutral.

Note: Electrons are the only carrier transferring in this process, not the protons. The number of transferred electrons will be the same to the vacancy of electrons in the source material. So, it will create equal and opposite charges on both materials.