The particle transferred when two substances are rubbed together is an electron.

Here's why:

* Friction: When you rub two materials together, the friction causes some of the outer electrons of the atoms in one material to be transferred to the other material.

* Static Electricity: This transfer of electrons creates an imbalance of charges. The material that loses electrons becomes positively charged, and the material that gains electrons becomes negatively charged. This is what we call static electricity.

Let me know if you'd like more detail on how this process works!