Electrical Systems

# Electrical Units 101

This class provides a foundational overview of electricity, including fundamental units and terminology. Electricity is the flow charged particles such as electrons. The number of valence electrons in an atom determines how well it allows electricity to flow. There are two types of electricity, alternating current and direct current, but both flow from negative to positive. The flow of electricity is measured by its amperage, voltage, resistance, and wattage. Ohm’s Law and Watt’s Law describe the relationships between these values in a circuit.

When working with electrical systems, knowing how electricity flows is critical for safety and efficiency. After taking this class, users should be familiar with the fundamentals of electricity and the vocabulary used to describe it. This enables users to build an understanding of more advanced electrical concepts.

• Difficulty Beginner

• Format Online

• Number of Lessons 17

• Language English

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Course Outline
• Electricity
• Parts of an Atom
• Valence Shells
• Ions
• Electricity and Atoms Review
• Conductors and Insulators
• Semiconductors
• Circuits
• Electrical Theory
• Direct Current and Alternating Current
• Conductivity and Circuits Review
• Amperage
• Voltage
• Resistance
• Ohm's Law
• Wattage
• Electrical Measurements Review
Objectives
• Describe common sources of electricity.
• Identify the parts of an atom. Describe atomic numbers.
• Describe how the valence shell of an atom affects its electrical conductivity.
• Define ions. Describe how charged particles behave.
• Describe conductors. Describe insulators.
• Describe semiconductors.
• Identify the parts of a circuit.
• Distinguish between conventional current theory and electron theory.
• Distinguish between direct current and alternating current. Define hertz.
• Define coulomb. Define amperage.
• Define voltage.
• Define resistance.
• Describe Ohm's Law.
• Define wattage. Describe Watt’s Law.
Glossary
Vocabulary Term
Definition

alternating current

AC. Electricity that reverses direction at regularly recurring intervals of time. Alternating current switches direction at a frequency of 60 hertz in the United States.

aluminum

A highly-conductive, lightweight, silvery metal. Aluminum is often used in long-distance power distribution.

amp

A. A unit of measurement that indicates both an amount of electricity and the time it takes to travel a certain distance. One amp, or ampere, equals one coulomb per second.

amperage

I. The strength or intensity of an electrical current. Amperage is measured in amperes (A).

ampere

A. A unit of measurement that indicates both an amount of electricity and the time it takes to travel a certain distance. One ampere, or amp, equals one coulomb per second.

atomic number

A number that identifies an element by indicating the number of protons in the nucleus of each of its atoms. The atomic number of each element is unique because every element has a different number of protons.

atoms

The smallest distinguishable unit of a material that maintains that material's characteristics. Atoms are made up of protons, neutrons, and electrons.

batteries

A device that converts chemical energy into electrical energy. Batteries are a source of direct current.

bond

Two or more atoms sharing or transferring electrons. Bonding holds atoms together.

carbon

A common non-metallic element that exists in several forms. Carbon has an atomic number of six, and it can be conductive in some forms, such as graphite.

ceramics

A nonmetallic material made from clay and hardened by firing at a high temperature. Ceramic materials are used as insulators in power lines, circuit boards, and many other components.

charged

Having an electric charge. The charge of a particle determines how it reacts to electric and magnetic fields.

chemical

Relating to the interaction between substances. Chemical energy can be stored in batteries and then converted into electrical energy.

chemical reactions

A process in which one or more substances are changed into another substance or substances. Chemical reactions allow batteries to produce electricity.

chlorine

Cl. A light, abundant element that is toxic in gaseous form. Chlorine is highly reactive and used in a wide variety of chemical compounds.

circuit

A controlled path for electricity. A circuit includes a source, path, load, and control.

conductors

A material that allows free movement of charged particles and, therefore, allows easy flow of electricity. Conductors are often metals.

control

A component in a circuit that regulates the flow of electricity. A control can turn the electricity on or off or adjust the intensity of current.

conventional current theory

The practice of showing electricity in a circuit as moving from positive to negative. Conventional current theory is based on an outdated understanding of electrical current.

copper

A highly conductive, reddish-brown metal. Copper is often used as an electrical conductor in houses, buildings, and machinery.

coulomb

C. The smallest quantitative measurement of electrical current. A coulomb is equal to the charge carried by 6.24 x 10^18 (6,240,000,000,000,000,000) electrons.

current

The flow of electricity. Current strength is called amperage and is measured in amperes (A).

diameter

The distance from one edge of a circle to the opposite edge as measured through its center. Diameter measures the width of a circle.

diodes

A semiconductor device that allows electrical current to flow in one direction and blocks current from flowing in the opposite direction. Diodes combine a positive semiconductor and a negative semiconductor to control the direction of current flow.

direct current

DC. Electricity that travels in one direction. Direct current does not reverse the direction of flow.

distribution systems

A network of electrical components that provides electricity from the utility to specific end destinations. Distribution systems use generators, power lines, and transformers to deliver electric power to buildings and other structures.

electric vehicles

EV. A vehicle that is propelled by an electric motor that draws its power from a battery. Electric vehicles require high-energy, lightweight, rechargeable batteries.

electrical conductivity

A material's ability to convey electricity. A material's level of electrical conductivity depends on its atomic structure.

electrical energy

A form of energy created by the movement of charged particles. Electrical energy, which is also called electricity, can be converted into work such as light, heat, or motion.

electrical potential

The amount of energy needed to move an electric charge. The difference in electrical potential between two points is called voltage.

electricity

A form of energy created by the movement of charged particles. Electricity, which is also called electrical energy, can be converted into work such as light, heat, or motion.

electrolytes

A conductive solution that allows ions to move freely. Electrolytes are typically liquids or gels.

electromotive force

EMF. A measure of electrical pressure or potential. Electromotive force is also called voltage and is measured in volts (V)

electron theory

The practice of showing electricity in a circuit as moving from negative to positive. Electron theory is based on the movement of electrons in metal conductors, which are used as the path in most circuits.

electrons

An atomic particle with a negative charge. Electrons orbit the nucleus of an atom and can move from one atom to another.

elements

A basic substance consisting only of atoms that share the same number of protons. Elements include carbon, hydrogen, and oxygen.

energy

The ability to do work. Energy comes in many forms, including electrical, mechanical, thermal, and chemical.

fossil fuels

A naturally occurring organic fuel formed in the Earth's crust that can be burned to release stored energy. Fossil fuels include petroleum, coal, and natural gas.

free electrons

An electron that is not attached to an atom or molecule. Free electrons conduct electricity in metals.

frequency

The number of complete AC cycles that occur in one second. Frequency is measured in hertz (Hz).

generators

A device that converts mechanical energy into electrical power. Generators are a common electrical source.

germanium

A gray-white, crystalline metalloid that is hard and brittle. Germanium is a semiconductor.

glass

A brittle, hard material that is often transparent. Glass is often used as an electrical insulator on power lines.

heating elements

A device that converts electricity into thermal energy. Heating elements emit heat when current passes through them.

hertz

Hz. A unit of frequency equal to one cycle per second. The hertz is used to measure how often the direction of alternating current reverses.

hydroelectric power

The electricity produced by turbines that are turned by water flow. Hydroelectric power is created when the mechanical energy of the turbines is converted into electrical energy.

insulators

A material that has little electrical conductivity and high resistance to electrical charges. Insulators include rubber, plastic, and ceramics.

ions

A charged atom. Ions become charged by gaining or losing electrons.

lathe

A machine tool that is used to produce a range of parts from a cylindrical workpieces. On a basic lathe, the workpiece is rotated in the spindle while the cutting tool is guided along the workpiece to create a finished part.

lithium

A lightweight, silver-white metal that is highly reactive. Lithium has an atomic number of three, and it is often used in batteries because it is extremely energy dense.

A component in a circuit that converts electricity into other forms of energy such as light, heat, or mechanical motion. A load can be a lightbulb, appliance, machine, or other device.

machine tool

A power-driven machine that uses a cutting tool to create chips and remove metal from a workpiece. Common machine tools include lathes, mills, and drill presses.

matter

A substance that has mass and exists as a solid, liquid, or gas. Matter can change states based on temperature and pressure.

mechanical energy

Energy transmitted through physical interaction and motion. Mechanical energy can be converted to electrical energy by a generator.

metals

A hard substance that is electrically and thermally conductive. Metals are often described as shiny or lustrous in appearance.

molecules

A group of two or more atoms joined together by chemical bonds. A molecule may consist of atoms of the same element or atoms of two or more different elements.

motor

A machine that converts other forms of energy into mechanical energy. Motors often transform electrical energy into mechanical energy.

neutrons

An atomic particle with no charge. Neutrons are located in the nucleus of an atom.

nuclear power

The electrical energy generated by nuclear fission reactions. Nuclear power generation requires specialized radioactive materials.

nucleus

The central portion of an atom. The nucleus contains protons and neutrons and is orbited by electrons.

ohms

Ω. The unit used to measure electrical resistance. One ohm is equal to one volt divided by one amp.

Ohm's Law

The equation that describes the relationships between voltage, amperage, and resistance. Ohm's Law states that one volt equals one amp times one ohm.

particles

An extremely small piece of matter. Atoms are made up of particles called protons, neutrons, and electrons.

path

A conductor that directs electricity along a controlled route in a circuit. Paths are often made of copper wire.

power

The rate at which one form of energy is converted into another form. Power is measured in watts (W).

protons

An atomic particle with a positive charge. Protons are located in the nucleus of an atom.

resistance

R. The opposition to the flow of electric current. Resistance is measured in ohms (Ω).

rubber

An elastic substance that can be either natural or manufactured. Rubber is an electrical insulator widely used in personal protective equipment (PPE) for electrical work.

semiconductor

A material or element with an electrical conductivity level between that of a conductor and an insulator. Semiconductors typically have four valence electrons and include silicon and germanium.

semiconductor devices

An all-electrical component made from semiconductor materials. Semiconductor devices like diodes, transistors, and integrated circuits (ICs) are small, fast, reliable components.

shells

A round path that electrons follow when they orbit the nucleus of an atom. Shells can have different numbers of electrons, depending on their positions, and atoms can have multiple shells.

silicon

A lustrous, gray, semi-metallic material. Silicon is a semiconductor that is often used to make diodes, transistors, and other semiconductor devices.

silver

A soft, gray-white metal that has the highest electrical conductivity of all metals. Silver is often used as a conductor in electronic devices.

sodium

Na. A common element in the alkali metal group. Sodium is highly reactive and flammable at room temperatures.

sodium chloride

NaCl. A transparent, brittle mineral widely used in food, medicine, and manufacturing. Sodium chloride, which is also called table salt, is made from sodium and chlorine ions.

solar panels

A device that converts light energy into direct current electricity. Solar panels are made of semiconductors.

solar power

The electrical energy generated by sunlight. Solar power is a form of renewable energy.

source

The device that provides electrical power to a circuit. Common sources include batteries and generators.

sulfur

A brittle, yellow, non-metallic element. Sulfur compounds in gas form are used as insulators in high-voltage electrical power distribution.

table salt

NaCl. A transparent, brittle mineral widely used in food, medicine, and manufacturing. Table salt, which is also called sodium chloride, is made from sodium and chlorine ions.

Terminal

A conductive device within a circuit to which other components can be attached. Terminals have a negative or positive charge.

thermal

Relating to energy in the form of heat. Thermal energy can be converted into electrical energy.

transformed

Having voltage increased or decreased by a transformer. AC electricity is easily transformed.

Troubleshooting

The systematic elimination of the various parts of a malfunctioning system, circuit, or process to locate the source of the problem. Troubleshooting an electrical circuit often involves conducting visual inspection, consulting electrical prints, and using electrical testing instruments.

valence electron

An electron in the valence, or outermost, shell of an atom. Valence electrons influence resistance.

valence shell

The outermost orbit of electrons in an atom. The valence shell can have only eight electrons.

voltage

E. A measure of electrical pressure or potential. Voltage is also called electromotive forces and is measured in volts (V)

volts

V. A unit used to measure electromotive force or pressure, which is called voltage. One volt of force is needed to move one ampere of current through one ohm of resistance.

wattage

P. An amount of power as measured in watts (W). Wattage can be used to measure both the power provided by a circuit and the power consumed by a load.

watts

W. A unit of measurement for the power produced by a circuit or used by loads. A watt is equal to the work performed when one amp moves across an electrical potential of one volt.

Watt's Law

The equation that describes the relationships between wattage, amperage, and voltage. Watt's Law states that one watt equals one amp times one volt.

wind power

The electrical energy generated by the movement of wind turbines. Wind power is a form of renewable energy.

work

The result of electricity flowing through resistance. Work often appears in the form of heat, light, or motion.

work

The result of electricity flowing through resistance. Work usually appears in the form of heat, light, or motion.