This document discusses electric fields and forces. It explains that electric charge comes from electrons and protons in atoms, and that rubbing materials together can transfer electrons, creating a separation of positive and negative charges. It also describes how conductors, insulators, and semiconductors differ in how easily they allow charge to flow through or remain separated.

1. Electric Fields and Forces

2. Electrification by Friction Electric charge, or `electricity', can come from batteries and generators. But some materials become charged when they are rubbed. Their charge is sometimes called electrostatic charge or `static electricity'. It causes sparks and crackles when you take off a pullover, and if you slide out of a car seat and touch the door, it may even give you a shock.

33. Positive Charge +

34. A hollow sphere