Summary

The Greeks discovered the first type of electricity in the form of static electricity when they observed that amber rubbed with fur would attract lightweight objects such as feathers. Static electricity is electricity at rest or without any motion. All matter is composed of atoms and electrical charge is a component of all atoms, so all matter is electrical in essence. An atom is the smallest part of an element that retains all of the properties of that element. All atoms share the same basic structure. At the center of the atom is the nucleus, containing protons, neutrons, and electrons. When an atom is balanced, the number of protons will match the number of electrons and the atom can be described as being in an electrically neutral state. The phenomenon we describe as electricity concerns the behavior of atoms that have become, for whatever reason, unbalanced or ionized. Electricity may be defined as the movement of free electrons from one atom to another.

An electrostatic charge can build up on the surface of your body. If you touch something, your charge can be discharged to the other surface, which is called electrostatic discharge (ESD).An automotive technician should always use a static grounding strap when working with staticsensitive electronic devices.

When light contacts certain materials, such as selenium and cesium, electron flow is stimulated and is called photoelectricity. Solar energy is light energy (photons) from the sun that is gathered in a photovoltaic solar cell. Aphoton is pure energy thatcontains no mass. Thermoelectricity is electricity produced when two dissimilar metals are heated to generate an electrical voltage. Athermocouple is a small device made of two dissimilar metals that gives off a low voltage when heated. Piezoelectricity is electricity produced when materials such as quartz or barium titanate are placed under pressure. The production of electricity from chemical energy is demonstrated in the lead-acid battery. Electromagnetic induction is the production of electricity when a current is carried through a conductor and a magnetic field is produced.

Andre Marie Ampere established the importance of the relationship between electricity and magnetism. Alessandro Volta discovered that if two dissimilar metals were brought in contact with a salt solution, a current would be produced; this invention is now known as the battery. George Simon Ohm showed a relationship between resistance, current, and voltage in an electrical circuit; he developed what is known as Ohm’s Law. James Watt developed a method used to express a unit of electrical power known as Watt’s Law.