# Charging by friction

Why does charging by friction charges an insulating material even if an insulator does not allow flow of electrons between an object to another? Is it because of the TriboElectric effect but doesn't it violate the law with the material being an insulator?

Does being a conductor or an insulator affect charging by friction?

The friction energy $E$ is transferred to the electrons on the outside layer which are in this way freed from their bonds.
On the other hand if both materials are conductors while the objects are in touch there is going to be a current flow back from where they came creating heat in the process due to $P=RI^2$ - for example train tracks and train wheel when the train is suddenly stopping - you will see sparks and if you touch the wheel it's going to be hot.