Conductors and Insulators, Free Charges and Bound Charges Inside a Conductor

A familiar everyday observation motivates this section: touching a bare wire in wet conditions, or the metal door handle of a car, can produce a mild but noticeable electric shock, while touching a piece of dry wood almost never does. The physical reason is that a "shock" is simply the sensation of a brief current -- a flow of electrons -- passing through the body when it comes into electrical contact with another charged or differently-charged body, whether by direct touch or by rubbing. …