The following terms may be used throughout this section. Note that some glossary terms may be in italics throughout the section content but are not included in this list. A complete list of terms for Section C-2 can be found in the Glossary. 

• AC generator: A machine that makes electricity by spinning a coil or magnet, producing alternating current (AC). (Section C-2.1)
• alternating current (AC): Electricity that flows back and forth in a circuit many times per second. (Section C-2.1)
• American wire gauge (AWG) system: A standard way to measure how thick electrical wires are. Smaller numbers mean thicker wires. (Section C-2.1)
• ammeter: A tool used to measure how much electrical current is flowing in a circuit. (Section C-2.1)
• Ampere’s Force Law: A law that explains how electricity flowing through a wire creates a magnetic force that can act on other wires carrying current. (Section C-2.1)
• anode: The electrode where electric current leaves a device or where oxidation happens in a chemical reaction. (Section C-2.1 and Section C-2.2)
• block diagram (functional block diagram; block and line diagram): A diagram that shows how parts of a system work together in steps. (Section C-2.3)
• cathode: The electrode where electric current enters a device or where reduction happens in a chemical reaction. (Section C-2.1)
• cation: A positively charged ion (an atom that has lost electrons). (Section C-2.1)
• circuit breaker: A safety device that automatically shuts off electricity when too much current flows. (Section C-2.1)
• clamp-on ammeter: A tool that measures current by clamping around a wire without touching it directly. (Section C-2.4)
• closed circuit: A complete path that allows electricity to flow. (Section C-2.1)
• conductor: A material, usually metal, that allows electricity to flow easily. (Section C-2.1)
• continuity: When electricity can flow through a circuit without a break. (Section C-2.4)
• coulomb: A unit used to measure electric charge. (Section C-2.1)
• current (amperage): The flow of electrical charge through a circuit. (Section C-2.1)
• direct current (DC): Electricity that flows in one direction only. (Section C-2.1)
• electrical symbols: Simple drawings used to represent electrical parts in a diagram. (Section C-2.3)
• electrical circuit: A complete path that allows electricity to travel from a source, through components, and back again. (Section C-2.1)
• electricity: The flow of tiny particles called electrons through a material, usually a wire. (Section C-2.1)
• electromagnetism: The force created by electricity and magnetism working together, such as when electric current makes a magnet. (Section C-2.1)
• electromotive force (EMF): Another name for voltage; the force that pushes electricity through a circuit. (Section C-2.2)
• fuse: A safety device that melts and breaks a circuit if too much current flows. (Section C-2.1)
• induction: The process of creating electrical current using a changing magnetic field. (Section C-2.1)
• in series: A way of connecting a meter so that electricity must flow through the meter as part of the circuit, allowing all the electrical current to flow through it before moving on. (Section C-2.4)
• load: A device that uses electrical energy to do work, such as producing heat, light, or motion. (Section C-2.1)
• magnetic field: An invisible area around a magnet or electrical current where magnetic forces can be felt. (Section C-2.1)
• milliamps (mA): A unit used to measure small electrical currents; 1 milliamp equals 0.001 amps; small amounts of electrical current measured by a meter, where one milliamp equals one-thousandth of an amp. (Section C-2.4)
• multimeter: A tool that can measure voltage, current, and resistance in a circuit. (Section C-2.3; Section C-2.4)
• Ohm’s law: A rule that shows the relationship between voltage, current, and resistance in a circuit. (Section C-2.1)
• open circuit: A broken path that prevents electricity from flowing. (Section C-2.1)
• parallel circuit: A circuit with more than one path for electricity to flow. (Section C-2.1)
• pictorial diagram (or schematic): A diagram that shows electrical parts as they actually look in real life. (Section C-2.3)
• polarity: The arrangement of positive and negative connections in a circuit, which determines the direction electricity flows; the correct way to connect meter leads to positive (+) and negative (−) points so the meter reads properly. (Section C-2.4)
• power: The rate at which electrical energy is used or converted into other forms of energy. (Section C-2.1)
• relay: An electrically controlled switch that uses a small current to control a larger one. (Section C-2.1)
• resistance: The opposition to the flow of electrical current in a circuit. (Section C-2.1)
• schematic diagram (ladder diagram): A diagram that uses symbols to show how an electrical circuit works. (Section C-2.3)
• series circuit: A circuit with only one path for electricity to follow. (Section C-2.1)
• single-phase power: A type of electrical power that uses one alternating voltage supply, commonly found in homes. (Section C-2.1)
• solenoid valve: A valve that opens or closes using an electric current and a magnetic coil. (Section C-2.1)
• switch: A device used to open or close a circuit to control the flow of electricity. (Section C-2.1)
• thermocouple: A device made of two different metals that produces a small voltage when heated, used to measure temperature. (Section C-2.1)
• thermoelectricity (thermoelectric effect): The creation of electricity from heat differences between two materials. (Section C-2.1)
• three-phase power: A type of electrical power that uses three alternating voltages, commonly used in commercial and industrial settings. (Section C-2.1)
• transformer: A device that increases or decreases voltage in an alternating current (AC) circuit. (Section C-2.1)
• voltage: The electrical pressure that pushes current through a circuit. (Section C-2.1)
• voltage drop: The loss of voltage as electricity moves through a circuit or component. (Section C-2.1)
• voltmeter: A tool used to measure the voltage between two points in a circuit. (Section C-2.3)
• wiring diagram: A drawing that shows how wires and components are connected in a circuit. (Section C-2.3)
• watt (W): The unit used to measure electrical power. (Section C-2.1)