Electrotechnology Today's Magic
Try to imagine a world without electricity. A world with no lights, cell phones, cameras, microwave ovens, iPods, video games or computers. A world without air conditioners, radar, laser beams, power stations or a sophisticated national power grid distributing electricity to our homes, schools, and businesses.
Hard to imagine? Of course.
If we had magical powers, a world without electricity might be something like Harry Potter's mythical world of wizards and witches who travel by steam engine when they are not flying on their brooms. Harry and friends have no electricity, but manage quite well with their spells and incantations. But, unless you've been able to enroll in Hogwarts School or have snitched some enchanted Floo Powder to travel via fireplace, you'll have to stick with electricity.
With bolt temperatures hotter than the surface of the sun and shockwaves beaming out in all directions, lightning is a lesson in physical science. (Photo courtesy: National Oceanic and Atmospheric Administration)
And why not? Electricityor what engineers call electrotechnologyis the closest thing to magic we have discovered and harnessed so far. Although it won't power a broomstick, it has helped to take us to the moon and has changed every aspect of our lives here on Earth. It's hard to imagine a time without electricity. It has been part of our lives for so long that even our great grandfathers, who may harbor memories of horse drawn buggies, can't remember a time when they couldn't flick a switch and watch a glass bulb "magically" brighten a dark space.
It All Starts With Electricity
Electrotechnology is a word that literally means the technological application of electricity. We see it all around us in the devices that make our lives richer and more convenientfrom computers to TVs to cell phones. Broadly applied, it means just about everything electrical. But, what is electricity? It is a naturally occurring form of energy. Electricity starts with electrons.
All matter is made up of atoms, and an atom has a core, called a nucleuswhich contains positively charged particles called protons and uncharged particles called neutrons. The nucleus of an atom is surrounded by negatively charged particles called electrons. The negative charge of an electron is equal in magnitude to the positive charge of a proton and the number of electrons in an atom is usually equal to the number of protons. When the balancing force between protons and electrons is upset by an outside force, an atom may gain or lose an electron. When electrons are "lost" from an atom, the free movement of these electrons constitutes an electric current.
We know today that electricity is all around us, an essential part of nature. But that wasn't quite so clear to the ancients and it took thousands of years to translate the Cave Man's awe of electrically charged Stone-Age thunderstorms into a working light bulb.
The Rhyme of the Ancient Greek Amber
The Ancient Greeks noticed if they rubbed a piece of amber, feathers would stick to it. Amber is the fossilized sap of ancient trees that forms through a natural polymerization of the original organic compounds. Most of the world's amber is in the range of 30-90 million years old. Amber is known to mineralogists as succinite, from the Latin succinum. The Greek name for amber is elektron, the origin of our word electricity. As smart as they might have been, the Greeks really couldn't explain why the feathers were sticking to the mineral. Today, we call this static electricity, something we encounter whenever we take warm socks out of the dryer. Or rub a balloon against our hair and stick it to a wall.
Ancient Greeks knew rubbing amber generated static electricity, but they didn’t know why. The Greek word for amber is elektron. (Photo courtesy: IEEE Virtual Museum)
It took a while before scientists started doing experiments using friction to generate static electricity. These experiments eventually led to machines that could produce large amounts of static electricity on demand. In 1660 the German scientist Otto von Guericke made the first electrostatic generator with a ball of sulfur and some cloth. After the development of static electric generating machines, early electrical experimenters generated high-voltage electrical currents, but they had no way to store this electricity until the mid-18th century. In 1746, Pieter van Musschenbroek of Leyden, Holland wrapped a water-filled jar with metal foil and discovered that this simple device could store the energy produced by an electrostatic generator. This device became known as the Leyden jar. It also was referred to as a "condenser" because many people thought of electricity as fluid, or matter that could be condensed. With a Leyden jar, an experimenter could store an electrical charge and move it to another place to use. Soon, Leyden jars were incorporated into the construction of frictional static-generating machines to make larger, longer sparks.
Think About It: Real Life Hogwarts In Pennsylvania
There is a group of people in this country, as many as 100,000, who live life like they were at Hogwarts, yet they will never see a Harry Potter movie. Or any movie for that matter because they don't believe in using electricity. These people are known as "the Amish," and they get around in horse-drawn buggies and use lanterns for light. The Amish believe in literal interpretation of the Bible. A member of the Amish Church must live a simple life devoted to God, family, and community. The Amish use very little electricity and avoid automobiles, television, and modern clothing. You may have heard of the Amish from the film Witness starring Harrison Ford and Kelly McGillis.
The Amish use very little electricity and avoid automobiles. (Photo courtesy: Pennsylvania Dutch Convention & Visitors Bureau)
If you think about it, they are the most non-technological folks around. They do make concessions to electricity when they use it to operate their modern dairy barns. Gas or diesel generators are employed to produce the needed electricity.
Just after the first appearance of Musschenbroek's device, William Watson, an English physician and scientist, constructed a more sophisticated version of the Leyden jar; he coated the inside and outside of the container with metal foil to improve its capacity to store charges. Watson transmitted an electric spark from his device through a wire strung across the River Thames at Westminster Bridge in 1747.
A Leyden jar from about the 1910s. (Photo courtesy: IEEE Virtual Museum/David Rickert)
The Leyden jar was a revolution in the study of electrostatics. In 1746 the Abbé Jean-Antoine Nollet, a physicist who popularized science in France, discharged a Leyden jar in front of King Louis XV by sending current through a chain of 180 Royal Guards. Later, Nollet used wire made of iron to connect a row of Carthusian monks more than a kilometer longwhen a Leyden jar was discharged, the white-robed monks reportedly leapt simultaneously into the air from the jolt. Warning: never, ever, try to shock anyone with electricity. Even a small charge can hurt someone.
Benjamin Franklin and His Kite
Jumping French monks aside, not all the cool experiments were in Europe. In the United States, Philadelphia inventor Benjamin Franklin sold his printing house, newspaper, and almanac to spend his time conducting electricity experiments. In 1752, Franklin attached a key to a silk kite and flew it in a storm-threatened sky. When a thundercloud moved by, the key sparked. This sent a spark, charging the Leyden jars and proving that lightning was really electricity. He then used the accumulated charge from the lightning to perform electric experiments. Franklin articulated the law now known as the Conservation of Charge (the net sum of the charges within an isolated region is always constant).
Please note: For all you would-be Franklins out there, Franklin did not fly a kite in an actual storm. NEVER do that!
What Is Lightning?
Amber may be cool and static electricity is kind of wacky, but neither has the power of lightning. Lightning is so hot it's cool. Who can't remember being terrified sitting in a dark room in the middle of a thunderstorm, watching flashes of lightning briefly illuminate the yard and then bracing for lightning's frequent companionthunder. Lightning is one of the most beautiful displays in nature. It is also one of the most lethal natural phenomena known. Lightning is a powerful natural electrostatic discharge produced during a thunderstorm. Lightning's abrupt electric discharge is accompanied by the emission of light. The electricity passing through the discharge channels rapidly heats and expands the air into a plasma, producing lightning's characteristic thunder sound. With bolt temperatures hotter than the surface of the sun and shockwaves beaming out in all directions, lightning is a lesson in physical science.
I saw the lightning's gleaming rod
Reach forth and write upon the sky
The awful autograph of God.
Joaquin (Cincinnatus Hiner) Miller (1839-1913)
There are many types of lightning , a short list includes intracloud lightning, sheet lightning, anvil crawlers, cloud-to-ground lightning, bead lightning, ribbon lightning, staccato lightning, cloud-to-cloud lightning and heat or summer lightningwhich is nothing more than the faint flashes of lightning on the horizon from distant thunderstorms. Don't forget the spooky X-Files-like ball lightning, described as a floating, illuminated ball that occurs during thunderstorms. Several theories have been advanced to describe the origins of ball lightning with none being universally accepted.
Ok, so how does it work? Although we know lightning is generated in electrically charged storm systems, the exact method of cloud charging still remains a mystery. In an electrical storm, the storm clouds are charged like giant sky-born capacitorsdevices that adjust and store current. When a voltage is applied to the surfaces, energy is stored in the resulting electric field created by the charge separation of the surfaces. The upper portion of the cloud is positive and the lower portion is negative. How the cloud acquires this charge is still not certain.
When the clouds' electric field becomes sufficiently strong, an electrical discharge occurs within the clouds or between the clouds and the ground, producing the lightning bolt. It has been suggested that these discharges are triggered by cosmic ray strikes which ionize atoms, releasing electrons that are accelerated by the electric fields, ionizing other air molecules and making the air conductive, then starting a lightning strike. The air within a lightning strike can heat up to 54,000 degrees Fahrenheit. To put that in perspective, that is nearly six times hotter than the surface of the sun. In other words the average flash will light a 100watt bulb for more than 3 months.
Volta Charges The First Battery
Unless you are Thor, the Norse god of thunder, it's really hard to harness a storm to generate electricity. Scientists sought other means. In 1800, Alessandro Volta of Italy built the Voltaic Pile and discovered the first practical method of generating electricity. Built of alternating discs of zinc and copper, with pieces of cardboard soaked in salty brine between the metals, the voltaic pile produced electrical current. Volta's voltaic pile was actually the first battery that produced a reliable, steady current of electricity. But, it's not like you could have plugged Volta's pile into your Discman for the drive to school. It was big, ugly, and messy, but it worked. His work was so important that the term voltthe unit of electric potentialis named in his honor.
Hello, Is Amp Here and Watts In A Volt?
For those of you who don't know your watts from your volts or amps, here's a quick primer.
Watt (symbol: W): The standard unit of measurement of electrical power. One watt is one ampere of current flowing at one volt. Watts are typically rated as AMPS x VOLTS or VOLT-AMP (V-A). However, this rating is only equivalent to watts when it applies to devices that absorb all the energy, such as electric heating coils or incandescent light bulbs. With computer power supplies, the actual watt rating is only 60% to 70% of the VOLT-AMP rating. The unit watt is named after inventor James Watt for his contributions to the development of the steam engine.
Volt (symbol: V): A unit of measurement of force, or pressure, in an electrical circuit. The common voltage of a United States AC power line is 120 volts of alternating current (alternating directions). Common voltages within a computer are from 3 to 12 volts of direct current (one direction only). Named after Alessandro Volta who "piled up" the first battery.
Amp (AMPere): A measurement of electrical current in a circuit. Contrast with volts, which is a measure of force behind the current. Multiplying amps times volts gives you watts, the total measurement of power. The symbol for amp is A. One amp is 6,280,000,000,000,000,000 (6.28 x 1018) electrons passing by the point of measurement in one second. See the terms defined on their website.
Electrons Go To Work
So we've learned thus far that about 200 years ago, inventors had figured out how to capture this elusive, invisible force called electricity and even store it. But to really put electricity to work, something else was needed. Electricity needed to move. Think of an electrical circuit like water circulating in a network of pipes, driven by pumps in the absence of gravity. If there is a pressure difference between two points, then water flowing from the high pressure point to the low pressure point will be able to do work, such as driving a turbine. Electrons work the same way. Without the movement, the electrons might as well be just a puddle of water sitting in a bucket.
The moving electrons transmit electrical energy from one point to another. But, there has to be something to make the electricity flow from one point to another through the conductor. One way to get electricity flowing is to use a generator. A generator uses a magnet to get electrons moving. In the 1830s, groundbreaking experiments in the new field of electromagnetism were conducted by British scientist Michael Faraday. He showed that when you move a loop of a wire in a magnetic field, a little bit of current flows through the loop for just a moment. This is called induction. Faraday also invented a machine that kept a loop of wire rotating near a magnet continuously. By touching two wires to the rotating loop, he could detect the small flow of electric current. This machine used induction to produce a flow of current as long as it was in motion, and so it was called an electromagnetic generator. And, as its name implies, it can generate electricity.
You Can Build an Electromagnet
Let's conduct a little science experiment of our own and build a battery-powered electromagnet-which shares most of the properties of regular bar magnets, which you have probably used. All magnets pick up steel or iron objects and they have two poles, one north and the other south. Opposites attract and likes repel. An electromagnet is the same, except it is temporary-it only has a magnetic field when electric current is flowing.
Joseph Henry’s large horseshoe shaped electromagnet from 1831. Henry used it in experiments. (Photo courtesy: IEEE Virtual Museum/Smithsonian Institution)
For your electromagnet, you will need a battery, say a normal D-cell from a flashlight, some paperclips, a medium size nail and some wire-thin copper wire from the local electronics store or four-strand telephone wire. Wrap your wire around a nail 10 times, connect the wire to each end of the battery. Bring the nail near the paperclips and watch as it picks them up. In fact, the nail behaves just like a bar magnet. However, the magnet exists only when the current is flowing from the battery.
Generators work by capitalizing on the link between the two invisible forces of nature, electricity and magnetism. If you allow electrons to move through a wire, they will create a magnetic field around the wire. Similarly, if you move a magnet near a wire, the magnetic field will cause electrons in the wire to move. An electric generator is a device for converting mechanical energy motion into electrical energy. The large generators used by the electric utility industry however, have a stationary conductor. A magnet attached to the end of a rotating shaft is positioned inside a stationary-conducting ring that is wrapped with a long, continuous piece of wire. When the magnet rotates, it induces a small electric current in each section of wire as it passes. Each section of wire constitutes a small, separate electric conductor. All the small currents of individual sections add up to one current of considerable size. This current is what is used for electric power.
Whether the source of electricity is a generator or battery, it will have two terminals: a positive terminal and a negative terminal. The source of electricity will push electrons out of its negative terminal at a certain voltage. For example, an AA battery typically tends to push electrons out at 1.5 volts. Once pushed, the electron will flow from the negative terminal to the positive terminal through a copper wire or some other conductor. When there is a path that goes from the negative to the positive terminal, you have a circuit, and electrons can flow through the wire. Somewhere in the middle of the circuit, attach a bulb (or a DVD player, a motor, a fan, etc.) and the source of electricity will power the load.
A lamp used at the historic 1879 New Year’s Eve demonstration of the Edison Lighting System in Menlo Park, New Jersey. (Photo courtesy: IEEE Virtual Museum/The Henry Ford Museum and Greenfield Village)
In a flash, people realized electricity and magnetism were interconnected and they took the first steps toward putting them to work. The very first machines were tiny and hardly seem useful compared to the electronic gadgets we use today. But 200 years ago, when the Industrial Revolution was getting under way in Europe, they were major breakthroughs. In the 19th century, inventors began looking for ways to use electromagnetism to run machines, which was being done at that time by steam engines, water wheels, horses, or even people. Later in 1879, when inventor Thomas Edison (remember him from the last issue on music technology?) demonstrated his incandescent lamp in Menlo Park, NJ, indoor lighting was born. Prior to 1879, electricity had been used in arc lights for outdoor lighting.
How Does A Light Bulb Work?
Light bulbs (known as incandescent bulbs) are quite simple; they are brilliant and relatively unchanged since Edison's time. The bulb has two metal contacts at the bottom of the base from where they draw their power. Connected to these contacts are two stiff wires, which are attached to a thin metal filament made of tungsten-which is very tough and can be heated to high temperatures. The filament sits in the middle of the bulb, held up by a glass mount. The wires and the filament are housed in a glass bulb, which is filled with a non-reacting element, such as argon. The filament, which is the part that glows when a bulb is switched on, is tremendously long and thin. For example, a standard 60-watt bulb filament is over six feet long, less than one-hundredth of an inch in diameter and is wound in a special fashion so the actual coil is less than an inch long.
Turn on a light switch and the electrical current heats up the filament. The electrons that make up the electrical current zip along, slamming into the tungsten atoms and causing them to vibrate-in other words, the current heats the atoms up. This friction produces heat or thermal energy, which is captured and then released by the electrons in the form of photons or light. Metal atoms release mostly infrared light photons, which are invisible to the human eye. But if they are heated to a high enough level, around 4,000 degrees Fahrenheit, they will emit a good deal of visible light.
Bringing It All Home
But all these devices still needed a reliable system of generating and distributing electrical power. What good is a light bulb if you have no place to plug it in? Enter our friend Mr. Edison again. In 1882, Edison opened the Pearl Street Station in New York City. It was the world's first commercial power plant. Although it was an enormous plant for its day, the station was able to produce and distribute electricity to only one square mile of lower Manhattan. Mostly successful, Edison's system had severe limitations because it used direct current (DC), which was not ideal for delivering electricity over long distances. Alternating current (AC) was better suited to the job and in the mid-1880s George Westinghouse began to set up AC power systems across the country. Most were water-powered, that is they were built alongside waterfalls (a primary source of mechanical energy) which turned water wheels which powered the electrical generators. AC was declared the universal form of power transmission in 1896 when a new AC power plant opened at Niagara Falls in 1895 and was used to light up portions of Buffalo, NY. Its successful use in transmitting large amounts of power to distant places was the deciding factor.
Electrical appliances changed the way people ran households. Before electricity generation began, houses were lit with kerosene lamps, food was cooled in iceboxes, and rooms were warmed by wood-burning or coal-burning stoves. Once electricity became reliable and widely available at low cost, inventions followed. In 1908, the vacuum cleaner came on the market. Five years later the electric refrigerator appeared. Air conditioning appeared at about the same time. Washing machines and dishwashers soon came on the scene. In 1935, the clothes dryer was invented.
Today we get electricity, which is a secondary energy source, from the conversion of other sources of energy, like coal, natural gas, oil and nuclear power, which are called primary sources. Most of the electricity in this country is produced in steam turbines. A turbine converts the kinetic energy of a moving fluid (liquid or gas) to mechanical energy. Steam turbines have a series of blades mounted on a shaft against which steam is forced, thus rotating the shaft connected to the generator.
Looking Toward Tomorrow
JToday's engineers are looking for ways to make older power plants more efficient and to exploit the untapped sources of energy all around us, like wind power, solar rays, and alternative fuels, says Dr. Hardy Pottinger, professor emeritus of Electrical and Computer Engineering at the University of Missouri-Rolla. He notes that salvation from laptop battery recharger purgatory may be on the way from a pioneering company called Neah Power Systems. Neah promises to make batteries go away through use of its unique micro fuel-cell technologythe same stuff used in space flight.
Then there's the Smart House, which debuted in September 2005 at the Open House and Exposition in Chicago. There have been attempts to build a so-called "smart house" before. But this one is different, developers say. The ZigBee Alliance house includes a whole network of domestic awareness systems that alert you to a basement flood or automatically dim the lights at bedtime. The difference in this system is ease of use. You can install a light switch or moisture sensor anywhere by sticking it in a wall or floor--no drilling required. The system uses a ZigBee chip to communicate to a network, telling it to turn off a light or alert the moisture system.
Or how about transforming yourself into a speed-reading demon? 'Language-savvy' Jump! by Corpora, tackles the assault of information overload by enabling people to boil down large electronic documents for relevant details quickly and easily. It uses natural-language processing to break down noun phrases and identify subjects and verbs. A little further away on the horizon is the development of special morphware or software that would allow you to transform your cell phone into a music player and back again. Developers are working on magnetologic devices that would serve as the building blocks of these futuristic products.
It's true, we can't imagine life without electricityor electrotechnology. It has changed our lives and eased our burdens. "Technology has certainly made multi-tasking the rule, rather than the exception," says Greg Hill, electronic communications manager for IEEE-USA a unit of the Institute of Electrical and Electronics Engineers, Inc., the world's largest technical professional society. "And, sure, bugs, viruses and other glitches give us headaches, but, all in all, I think technology has made our lives easier. Things that we take for granted todayfrom looking up some obscure reference on Wikipedia to planning a vacation online to paying your bills every month automaticallythese are things that were unimaginable to the average citizen 10 or 15 years ago."
And remember, electrotechnology can be fun. Computers without electricity, for example, would be nothing more than big doorstops. Although it may not produce Harry Potter-like enchantment, taking you away on the Hogwarts Express, it's pretty close to having a real magic wand.
Check out the NSTEP Web site and click on TechXplore program and competition that connects teams of students with scientists and high-tech companies to explore the world of technology. If you want to create a TechXplore team at your school to explore technology, send an email to TechXplore@nstep-online.org.
TechXplore® is a registered trademark of the National Science & Technology Education Partnership.
Name: Greg Hill
Title: Electronic Communications Manager for the Washington DC-based IEEE-USA, an organizational unit of the Institute of Electrical and Electronics Engineers, Inc.the world's largest technical professional society.
His real job: "In a nutshell, my role at IEEE-USA is to employ the full range of electronic communications tools at our disposal to keep our members informed. That means working with different staff members and volunteer groups to promote a wide range of activities. I spend most of my day at my PC online, updating our Web sites, e-mailing authors, creating graphics, and editing articles."
School: BA, English, Pennsylvania State University.
Why he chose this career: "I really landed in my career by chance. I moved to Washington DC with my English degree and some experience working in the advertising department of a small newspaper, but not much of a clue where I wanted to go from there. A friend of mine helped me get a job selling construction information over the phone, but, mercifully, that didn't last long." Eventually, he first got a temp job at IEEE-USA in the Communications Department and later moved into a full-time position.
Was he a high school math/science wiz? "Not really, but I was in Advanced Placement calculus and I think I was okay at it. I do kind of wish I had stuck with math and science. I had some great teachers, but at that point in my life, I just didn't make the connection between the seemingly abstract concepts of math and real-world applications."
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What he does for fun: "My wife and I like to go for long walks down into Washington to walk around the monuments. I also enjoy playing soccer regularlyyes, even at 33 you can still run around and fall down just like you did when you were a kid. You just get up a little bit slower."
Advice: "I know it sounds like a cliché, but do your homework. A career in science or engineering is one full of challenges and rewards, but you have to do the homework. Reach out to scientists or engineers in your communityfrom local colleges or technology companiesand invite them to visit your school to talk to you and your classmates about their careers." To encourage that reaching out, IEEE-USA participates in a program where post-graduate engineering students are placed at major media outlets, such as Popular Science, Scientific American, and newspapers to bridge the gap between science and engineering. Participants write and assist on stories that have a science or engineering angle.
What is the driving force that fuels today's engineers? "Having worked with engineers for the better part of eight years, I've come to the conclusion that engineers are about as altruistic a group as there is. Engineers are problem solversit's what they are wired to do. They aren't motivated by greed or a need to be in the spotlight. Instead, they labor away, in obscurity sometimes, making things work better, safer, and easier."
Gazing at the crystal ball: The next big thing will probably be tiny, he says. "I just read about wrist watches that have incorporated tiny devices, such as MP3 players, cell phones and even one with a television. When I was a kid that was the stuff of Dick Traceyor Inspector Gadgetand I remember drawing cartoons of futuristic watches with TV screens and two-way radios. So, I guess that my answer is that if you can imagine it, engineers will eventually design and build it. The ever-shrinking integrated circuit and the emerging field of nanotechnology means technologies will be less intrusive and more integrated into the fabric of our lives."
- Academy of Energy: Provides an information-rich, action-based journey and enables access to learning resources for energy conservation.
- Boston's Museum Of Science
- Brief History of the Microwave
- DOE's Kids Zone: A robust portal for science and energy education, with age-grading of the many links to other Department of Energy educational sites.
- DOE Energy Calculator
- EduGreen: Created by Tata Energy Research Institute, New Delhi, India. There, you will find topics such as life on earth and climate change. Interactive features include games, quizzes, puzzles, and networking with others.
- U.S. Department of Energy Kid's Pages
- Energy Ed Online: A service of the Energy Center of Wisconsin, this site is geared toward promoting energy education programs within Wisconsin schools. The site includes an online course for K-12 educators.
- Energy Education Resources: Kindergarten Through 12th Grade: Published by the Energy Information Administration (EIA), this site lists generally free or low-cost energy related educational materials available for students and educators.
- The Galileo Project: A source of information on the life and work of Galileo Galilei (1564-1642). It provides information about Galileo and the science of his time to viewers of all ages and levels of expertise.
- History of Computing
- History of Science on The Web
- How A Capacitor Works
- IEEE Kid Friendly Links Page
- IEEE Spectrum Magazine
- Kid's World: An educational site developed by the Texas Railroad Commission. (You'll especially enjoy "Ask the Commissioners!")
- Learning Center: On Chevron Corporation's Web site. Children can get an idea about how a refinery operates and about the tools Chevron uses in the search for oil and natural gas; learn about the history and properties of crude oil; and find out what a Chevron service station is all about
- Leyden Jars
- Liberty Science Center
- Museum History Links Page
- The National Energy Foundation: A great resource for students and teachers. This organization is dedicated to the development, dissemination, and implementation of supplementary educational materials, programs, and courses, related primarily to energy, water, natural resources, science, and math, technology, conservation, and the environment. See fun activities for students at www.nef1.org/students.html
- The National Energy Education Development Project (NEED): A network of students, teachers, community organizations, government agencies, and corporations dedicated to learning about energy.
- Power History: The story of Powering a Generation of Change provides electricity basics and history, including an explanation of electricity restructuring in the U.S.
- Smithsonian Institution's Kids' Castle
- Socket To Me, IEEE's Virtual Museum
- The Space Place
- St. Louis Science Center
- The Toaster Museum: The collection now has a new physical home, moving from Oregon to Charlottesville, VA., the "Best Small City in the South."
- Try Science
- Women in Engineering Links
Alternating Current: An electric current that reverses its direction at regular intervals or cycles. In the U.S. the standard is 120 reversals or 60 cycles per second; typically abbreviated as AC.
Alternative Fuel: A popular term for "non-conventional" transportation fuels made from natural gas (propane, compressed natural gas, methanol, etc.) or biomass materials (ethanol, methanol).
Ampere: A unit of measure for an electrical current; the amount of current that flows in a circuit at an electromotive force of 1 Volt and at a resistance of 1 Ohm. Abbreviated as amp.
Battery: An energy storage device made up of one or more electrolyte cells.
Capacitor: Electrical devices that consist of two conductive surfaces separated by an insulating media used to store a charge temporarily (also called a condenser; see Leyden Jar).
Charge: Either the power stored in a battery or the fundamental characteristic of all electric and electrotechnological forces, expressed in two forms known as positive and negative. Also known as the excess or lack of electrons.
Circuit(s): An electrically conductive path containing wires and circuit elements (e.g. batteries, resistors and capacitors) through which electric current flows.
Conductor: An object or substance that conducts or allows electric current to flow easily. A wire, metal cable, metal rod, or metal tube can serve as a path for electricity to flow. The most common conductor is an electrical wire. Metals are excellent conductors.
Connection: A physical bond between two electrical systems that permits the transfer of energy.
Current: The rate of flow of electric charges.
Direct Current: (DC) Electric energy of constant value and flowing in one direction, usually produced by batteries, like those you would find around the house.
DOE: U.S. Department of Energy.
Electricity: A form of energy characterized by the presence and motion of elementary charged particles generated by friction, induction, or chemical change.
Electricity Generation: The process of producing electric energy or the amount of electric energy produced by transforming other forms of energy, commonly expressed in kilowatt-hours (kWh).
Electric Motor: A device that takes electrical energy and converts it into mechanical energy to turn a shaft.
Electromagnetic Energy: Energy that travels in waves at the speed of light, such as ultra-violet radiation and microwaves. It can be thought of as a combination of electric and magnetic energy.
Electron: A subatomic particle with a negative electric charge. Electrons form part of an atom and move around its nucleus.
Filament: The fine metal wire in a light bulb that glows when heated by an electric current passing through it
Horsepower: A unit for measuring the rate of work (or power) equivalent to 33,000 foot-pounds per minute or 746 watts.
Hydroelectric Power Plant: A power plant that uses moving water to power a turbine generator to produce electricity.
Incandescent Light Bulb: An incandescent bulb is a type of electric light in which light is produced by a filament heated by electric current. The most common example is the type you find in most table and floor lamps.
Induction: The process of producing an electrical or magnetic effect through the influence of a nearby magnet, electric current, or electrically charged body.
Joule: A metric unit for measuring work and energy, named after James Joule. It is equal to the work done when a 1 ampere current is passed through a resistance of 1 ohm for 1 second.
Kilowatt (kW): A unit of power, usually used for electric power or for energy consumption (use). A kilowatt equals 1,000 watts.
Kilowatt-hour (kWh): A measure of electricity consumption defined as a unit of work or energy, measured as 1 kilowatt (1,000 watts) of power expended for 1 hour. One kWh is equivalent to 3.6 million joules.
Leyden Jar: A device that early experimenters used to store electric energy. It was also referred to as a condenser because many people thought of electricity as fluid or matter that could be condensed. Nowadays someone familiar with electrical terminology would call it a capacitor.
Light: Radiant electromagnetic energy that an observer can see.
Magnet: Any piece of iron, steel, etc., that has the property of attracting iron or steel.
Mechanical Energy: The energy of motion used to perform work.
Ohm: The unit of resistance to the flow of an electric current. Its symbol is the Greek capital letter omega (Ω). The ohm is named for Georg Ohm, a German physicist who discovered the relationship between voltage and current.
Photon: A particle of light that acts as an individual unit of energy.
Plasma: A high-temperature, ionized gas composed of electrons and positive ions in such number that it is electrically neutral.
Power: The rate at which energy is transferred. Electrical energy is usually measured in watts. Proton: A subatomic particle with an electric charge of one positive unit; it is found in the nucleus of an atom. The proton is observed to be stable.
Semiconductor: Any material that has a limited capacity for conducting an electric current. Semiconductors are crystalline solids with impurities, such as silicon made impure with arsenic, that have an electrical conductivity between that of a conductor and an insulator. The conductivity is controlled by the amount of impurity. Used in computer chips.
Tesla Coil: A device for producing a high-frequency, high-voltage electric current.
Transformer: A device that converts the generator's low-voltage electricity to higher-voltage levels for transmission to the load center, such as a city or factory. It can also be used to step down voltage.
Transmission (Electric): The movement or transfer of electric energy over an interconnected group of lines between points of supply and points at which it is transformed for delivery to consumers or is delivered to other electric systems.
Volt (V): The volt is the International System of Units (SI) measure of electric potential or electromotive force.
Voltage: The difference in electrical potential between any two conductors or between a conductor and ground.
Water Turbine: A turbine that uses water pressure to rotate its blades. Primarily used to power an electric generator.
Watt: A metric unit of power, usually used in electric measurements, which gives the rate at which work is done or energy used. (See Kilowatt)
Wavelength: The distance, measured in the direction of progression of a wave, from any given point to the next point in the same phase (e.g. from the one peak of the wave to the next peak).
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Watch for these upcoming issues of TechXtra in 2006:
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Early Spring 2006: Medical Technology
Late Spring 2006: Security (Part 1)
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Electrical and Computer Engineering
University of Missouri-Rolla
IEEE - USA
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