Question

What may happen if-
1.a glass rod is rubbed with fur?
2.a glass rod is rubbed with silk cloth?
3.a ebonite rod is rubbed with fur?
4.a ebonite rod is rubbed with silk cloth?

Answer 1

1)As an example of the friction method, a glass rod rubbed with fur becomes negatively charged, but if rubbed with silk, becomes positively charged. 
2)When you are rubbing the glass rod with the silk cloth, electrons are stripped away from the atoms in the glass and transferred to the silk cloth. This leaves the glass rod with more positive than negative charge, so you get a net positive charge.
3) When you rub fur with ebonite rod, the chemical bond is formed between some parts of the the two surface. Rod has its electron more tightly bound than fur. So, fur donates electrons to the rod while electrons from rod won't come out. Due to excess of electrons in rod, it becomes negatively charged while the fur with lost electrons, becomes deficient of electrons. Thus, fur becomes positively charged.
4)When an ebonite stick is rubbed with a silk cloth, electrons are transferred from the silk to the stick, giving it a surplus of electrons. Because neutral materials have equal numbers of electrons and protons to balance out their charge, the rubbed stick possesses a net negative static charge.