Here's why:
* Electrons are loosely bound: Electrons in the outermost shell of an atom (valence electrons) are held less tightly to the nucleus than protons and neutrons in the atom's core.
* Friction and electron transfer: When you rub materials together (like the comb and silk), the friction causes some of the loosely bound electrons to be transferred from one material to the other.
* Static electricity: This transfer of electrons creates a separation of charge, leading to static electricity. The material that loses electrons becomes positively charged, and the material that gains electrons becomes negatively charged.
In the case of a plastic comb and silk, the silk typically has a higher affinity for electrons, so it pulls some of the electrons from the comb. This leaves the comb with a net positive charge and the silk with a net negative charge.
