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121-439: Electrical engineering is an engineering discipline concerned with the study, design, and application of equipment, devices, and systems that use electricity , electronics , and electromagnetism . It emerged as an identifiable occupation in the latter half of the 19th century after the commercialization of the electric telegraph , the telephone, and electrical power generation, distribution, and use. Electrical engineering

242-647: A degree in electrical engineering, electronic or electrical and electronic engineering. Practicing engineers may have professional certification and be members of a professional body or an international standards organization. These include the International Electrotechnical Commission (IEC), the National Society of Professional Engineers (NSPE), the Institute of Electrical and Electronics Engineers (IEEE) and

363-464: A mass-production basis, they opened the door for more compact devices. The first integrated circuits were the hybrid integrated circuit invented by Jack Kilby at Texas Instruments in 1958 and the monolithic integrated circuit chip invented by Robert Noyce at Fairchild Semiconductor in 1959. The MOSFET (metal–oxide–semiconductor field-effect transistor, or MOS transistor) was invented by Mohamed Atalla and Dawon Kahng at BTL in 1959. It

484-625: A variety of topics in electrical engineering . Initially such topics cover most, if not all, of the subdisciplines of electrical engineering. At some schools, the students can then choose to emphasize one or more subdisciplines towards the end of their courses of study. At many schools, electronic engineering is included as part of an electrical award, sometimes explicitly, such as a Bachelor of Engineering (Electrical and Electronic), but in others, electrical and electronic engineering are both considered to be sufficiently broad and complex that separate degrees are offered. Engineering Engineering

605-698: A broad range of more specialized fields of engineering , each with a more specific emphasis on particular areas of applied mathematics , applied science , and types of application. See glossary of engineering . The term engineering is derived from the Latin ingenium , meaning "cleverness". The American Engineers' Council for Professional Development (ECPD, the predecessor of ABET ) has defined "engineering" as: The creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination; or to construct or operate

726-407: A commercial scale, such as the manufacture of commodity chemicals , specialty chemicals , petroleum refining , microfabrication , fermentation , and biomolecule production . Civil engineering is the design and construction of public and private works, such as infrastructure (airports, roads, railways, water supply, and treatment etc.), bridges, tunnels, dams, and buildings. Civil engineering

847-425: A compass needle; of William Sturgeon , who in 1825 invented the electromagnet ; of Joseph Henry and Edward Davy , who invented the electrical relay in 1835; of Georg Ohm , who in 1827 quantified the relationship between the electric current and potential difference in a conductor ; of Michael Faraday , the discoverer of electromagnetic induction in 1831; and of James Clerk Maxwell , who in 1873 published

968-454: A conductor of uniform cross section, therefore, can be computed as where ℓ {\displaystyle \ell } is the length of the conductor, measured in metres [m], A is the cross-section area of the conductor measured in square metres [m ], σ ( sigma ) is the electrical conductivity measured in siemens per meter (S·m ), and ρ ( rho ) is the electrical resistivity (also called specific electrical resistance ) of

1089-533: A count of 2,000. There were fewer than 50 engineering graduates in the U.S. before 1865. In 1870 there were a dozen U.S. mechanical engineering graduates, with that number increasing to 43 per year in 1875. In 1890, there were 6,000 engineers in civil, mining , mechanical and electrical. There was no chair of applied mechanism and applied mechanics at Cambridge until 1875, and no chair of engineering at Oxford until 1907. Germany established technical universities earlier. The foundations of electrical engineering in

1210-526: A degree is usually four or five years and the completed degree may be designated as a Bachelor of Science in Electrical/Electronics Engineering Technology, Bachelor of Engineering , Bachelor of Science, Bachelor of Technology , or Bachelor of Applied Science , depending on the university. The bachelor's degree generally includes units covering physics , mathematics, computer science , project management , and

1331-420: A demand for machinery with metal parts, which led to the development of several machine tools . Boring cast iron cylinders with precision was not possible until John Wilkinson invented his boring machine , which is considered the first machine tool . Other machine tools included the screw cutting lathe , milling machine , turret lathe and the metal planer . Precision machining techniques were developed in

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1452-420: A device later named electrophorus that produced a static electric charge. By 1800 Alessandro Volta had developed the voltaic pile , a forerunner of the electric battery. In the 19th century, research into the subject started to intensify. Notable developments in this century include the work of Hans Christian Ørsted , who discovered in 1820 that an electric current produces a magnetic field that will deflect

1573-418: A few hundred amperes. Aside from the geometry of the wire, temperature also has a significant effect on the efficacy of conductors. Temperature affects conductors in two main ways, the first is that materials may expand under the application of heat. The amount that the material will expand is governed by the thermal expansion coefficient specific to the material. Such an expansion (or contraction) will change

1694-641: A general electronic component. The most common microelectronic components are semiconductor transistors , although all main electronic components ( resistors , capacitors etc.) can be created at a microscopic level. Nanoelectronics is the further scaling of devices down to nanometer levels. Modern devices are already in the nanometer regime, with below 100 nm processing having been standard since around 2002. Microelectronic components are created by chemically fabricating wafers of semiconductors such as silicon (at higher frequencies, compound semiconductors like gallium arsenide and indium phosphide) to obtain

1815-406: A large number—often millions—of tiny electrical components, mainly transistors , into a small chip around the size of a coin . This allowed for the powerful computers and other electronic devices we see today. Microelectronics engineering deals with the design and microfabrication of very small electronic circuit components for use in an integrated circuit or sometimes for use on their own as

1936-427: A momentum transfer. As discussed above, electrons are the primary mover in metals; however, other devices such as the cationic electrolyte (s) of a battery , or the mobile protons of the proton conductor of a fuel cell rely on positive charge carriers. Insulators are non-conducting materials with few mobile charges that support only insignificant electric currents. The resistance of a given conductor depends on

2057-495: A particle is nudged into the consumer, thus powering it. Essentially what is occurring is a long chain of momentum transfer between mobile charge carriers ; the Drude model of conduction describes this process more rigorously. This momentum transfer model makes metal an ideal choice for a conductor; metals, characteristically, possess a delocalized sea of electrons which gives the electrons enough mobility to collide and thus affect

2178-503: A profession in the later 19th century. Practitioners had created a global electric telegraph network, and the first professional electrical engineering institutions were founded in the UK and the US to support the new discipline. Francis Ronalds created an electric telegraph system in 1816 and documented his vision of how the world could be transformed by electricity. Over 50 years later, he joined

2299-417: A reducing atmosphere, then oxygen-free high conductivity copper (CW008A or ASTM designation C10100) may be used. Because of its ease of connection by soldering or clamping, copper is still the most common choice for most light-gauge wires. Silver is 6% more conductive than copper, but due to cost it is not practical in most cases. However, it is used in specialized equipment, such as satellites , and as

2420-400: A result, many engineers continue to learn new material throughout their careers. If multiple solutions exist, engineers weigh each design choice based on their merit and choose the solution that best matches the requirements. The task of the engineer is to identify, understand, and interpret the constraints on a design in order to yield a successful result. It is generally insufficient to build

2541-432: A subject of scientific interest since at least the early 17th century. William Gilbert was a prominent early electrical scientist, and was the first to draw a clear distinction between magnetism and static electricity . He is credited with establishing the term "electricity". He also designed the versorium : a device that detects the presence of statically charged objects. In 1762 Swedish professor Johan Wilcke invented

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2662-411: A technically successful product, rather, it must also meet further requirements. Constraints may include available resources, physical, imaginative or technical limitations, flexibility for future modifications and additions, and other factors, such as requirements for cost, safety , marketability, productivity, and serviceability . By understanding the constraints, engineers derive specifications for

2783-643: A testament to the ingenuity and skill of ancient civil and military engineers. Other monuments, no longer standing, such as the Hanging Gardens of Babylon and the Pharos of Alexandria , were important engineering achievements of their time and were considered among the Seven Wonders of the Ancient World . The six classic simple machines were known in the ancient Near East . The wedge and

2904-585: A thin plating to mitigate skin effect losses at high frequencies. Famously, 14,700 short tons (13,300 t) of silver on loan from the United States Treasury were used in the making of the calutron magnets during World War II due to wartime shortages of copper. Aluminum wire is the most common metal in electric power transmission and distribution . Although only 61% of the conductivity of copper by cross-sectional area, its lower density makes it twice as conductive by mass. As aluminum

3025-641: A unified theory of electricity and magnetism in his treatise Electricity and Magnetism . In 1782, Georges-Louis Le Sage developed and presented in Berlin probably the world's first form of electric telegraphy , using 24 different wires, one for each letter of the alphabet. This telegraph connected two rooms. It was an electrostatic telegraph that moved gold leaf through electrical conduction. In 1795, Francisco Salva Campillo proposed an electrostatic telegraph system. Between 1803 and 1804, he worked on electrical telegraphy, and in 1804, he presented his report at

3146-909: A useful purpose. Examples of bioengineering research include bacteria engineered to produce chemicals, new medical imaging technology, portable and rapid disease diagnostic devices, prosthetics, biopharmaceuticals, and tissue-engineered organs. Interdisciplinary engineering draws from more than one of the principle branches of the practice. Historically, naval engineering and mining engineering were major branches. Other engineering fields are manufacturing engineering , acoustical engineering , corrosion engineering , instrumentation and control , aerospace , automotive , computer , electronic , information engineering , petroleum , environmental , systems , audio , software , architectural , agricultural , biosystems , biomedical , geological , textile , industrial , materials , and nuclear engineering . These and other branches of engineering are represented in

3267-424: A variety of industries. Electronic engineering involves the design and testing of electronic circuits that use the properties of components such as resistors , capacitors , inductors , diodes , and transistors to achieve a particular functionality. The tuned circuit , which allows the user of a radio to filter out all but a single station, is just one example of such a circuit. Another example to research

3388-644: A way to distinguish between those specializing in the construction of such non-military projects and those involved in the discipline of military engineering . The pyramids in ancient Egypt , ziggurats of Mesopotamia , the Acropolis and Parthenon in Greece, the Roman aqueducts , Via Appia and Colosseum, Teotihuacán , and the Brihadeeswarar Temple of Thanjavur , among many others, stand as

3509-513: Is a broad discipline that is often broken down into several sub-disciplines. Although an engineer will usually be trained in a specific discipline, he or she may become multi-disciplined through experience. Engineering is often characterized as having four main branches: chemical engineering, civil engineering, electrical engineering, and mechanical engineering. Chemical engineering is the application of physics, chemistry, biology, and engineering principles in order to carry out chemical processes on

3630-469: Is a pneumatic signal conditioner. Prior to the Second World War, the subject was commonly known as radio engineering and basically was restricted to aspects of communications and radar , commercial radio , and early television . Later, in post-war years, as consumer devices began to be developed, the field grew to include modern television, audio systems, computers, and microprocessors . In

3751-441: Is an engineering discipline that deals with the convergence of electrical and mechanical systems. Such combined systems are known as electromechanical systems and have widespread adoption. Examples include automated manufacturing systems , heating, ventilation and air-conditioning systems , and various subsystems of aircraft and automobiles . Electronic systems design is the subject within electrical engineering that deals with

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3872-734: Is associated with anything constructed on or within the Earth. This discipline applies geological sciences and engineering principles to direct or support the work of other disciplines such as civil engineering , environmental engineering , and mining engineering . Geological engineers are involved with impact studies for facilities and operations that affect surface and subsurface environments, such as rock excavations (e.g. tunnels ), building foundation consolidation, slope and fill stabilization, landslide risk assessment, groundwater monitoring, groundwater remediation , mining excavations, and natural resource exploration. One who practices engineering

3993-497: Is called an engineer , and those licensed to do so may have more formal designations such as Professional Engineer , Chartered Engineer , Incorporated Engineer , Ingenieur , European Engineer , or Designated Engineering Representative . In the engineering design process, engineers apply mathematics and sciences such as physics to find novel solutions to problems or to improve existing solutions. Engineers need proficient knowledge of relevant sciences for their design projects. As

4114-654: Is divided into a wide range of different fields, including computer engineering , systems engineering , power engineering , telecommunications , radio-frequency engineering , signal processing , instrumentation , photovoltaic cells , electronics , and optics and photonics . Many of these disciplines overlap with other engineering branches, spanning a huge number of specializations including hardware engineering, power electronics , electromagnetics and waves, microwave engineering , nanotechnology , electrochemistry , renewable energies, mechatronics/control, and electrical materials science. Electrical engineers typically hold

4235-404: Is not exact: It assumes the current density is totally uniform in the conductor, which is not always true in practical situation. However, this formula still provides a good approximation for long thin conductors such as wires. Another situation this formula is not exact for is with alternating current (AC), because the skin effect inhibits current flow near the center of the conductor. Then,

4356-404: Is passed through it. Liquids made of compounds with only covalent bonds cannot conduct electricity. Certain organic ionic liquids , by contrast, can conduct an electric current. While pure water is not an electrical conductor, even a small portion of ionic impurities, such as salt , can rapidly transform it into a conductor. Wires are measured by their cross sectional area. In many countries,

4477-650: Is roughly one-third the cost of copper by weight, the economic advantages are considerable when large conductors are required. The disadvantages of aluminum wiring lie in its mechanical and chemical properties. It readily forms an insulating oxide, making connections heat up. Its larger coefficient of thermal expansion than the brass materials used for connectors causes connections to loosen. Aluminum can also "creep", slowly deforming under load, which also loosens connections. These effects can be mitigated with suitably designed connectors and extra care in installation, but they have made aluminum building wiring unpopular past

4598-796: Is still important in the design of many control systems . DSP processor ICs are found in many types of modern electronic devices, such as digital television sets , radios, hi-fi audio equipment, mobile phones, multimedia players , camcorders and digital cameras, automobile control systems, noise cancelling headphones, digital spectrum analyzers , missile guidance systems, radar systems, and telematics systems. In such products, DSP may be responsible for noise reduction , speech recognition or synthesis , encoding or decoding digital media, wirelessly transmitting or receiving data, triangulating positions using GPS , and other kinds of image processing , video processing , audio processing , and speech processing . Instrumentation engineering deals with

4719-428: Is the design and manufacture of physical or mechanical systems, such as power and energy systems, aerospace / aircraft products, weapon systems , transportation products, engines , compressors , powertrains , kinematic chains , vacuum technology, vibration isolation equipment, manufacturing , robotics, turbines, audio equipments, and mechatronics . Bioengineering is the engineering of biological systems for

4840-589: Is the international standard to which all other electrical conductors are compared; the International Annealed Copper Standard conductivity is 58 MS/m , although ultra-pure copper can slightly exceed 101% IACS. The main grade of copper used for electrical applications, such as building wire, motor windings, cables and busbars , is electrolytic-tough pitch (ETP) copper (CW004A or ASTM designation C100140). If high conductivity copper must be welded or brazed or used in

4961-404: Is the practice of using natural science , mathematics , and the engineering design process to solve technical problems, increase efficiency and productivity, and improve systems. Modern engineering comprises many subfields which include designing and improving infrastructure , machinery , vehicles , electronics , materials , and energy systems. The discipline of engineering encompasses

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5082-459: Is their power consumption as this is closely related to their signal strength . Typically, if the power of the transmitted signal is insufficient once the signal arrives at the receiver's antenna(s), the information contained in the signal will be corrupted by noise , specifically static. Control engineering focuses on the modeling of a diverse range of dynamic systems and the design of controllers that will cause these systems to behave in

5203-664: Is traditionally broken into a number of sub-disciplines, including structural engineering , environmental engineering , and surveying . It is traditionally considered to be separate from military engineering . Electrical engineering is the design, study, and manufacture of various electrical and electronic systems, such as broadcast engineering , electrical circuits , generators , motors , electromagnetic / electromechanical devices, electronic devices , electronic circuits , optical fibers , optoelectronic devices , computer systems, telecommunications , instrumentation , control systems , and electronics . Mechanical engineering

5324-404: Is usually insulated with PVC insulation that is only rated to operate to about 60 °C, therefore, the current in such wires must be limited so that it never heats the copper conductor above 60 °C, causing a risk of fire . Other, more expensive insulation such as Teflon or fiberglass may allow operation at much higher temperatures. If an electric field is applied to a material, and

5445-567: Is very useful for energy transmission as well as for information transmission. These were also the first areas in which electrical engineering was developed. Today, electrical engineering has many subdisciplines, the most common of which are listed below. Although there are electrical engineers who focus exclusively on one of these subdisciplines, many deal with a combination of them. Sometimes, certain fields, such as electronic engineering and computer engineering , are considered disciplines in their own right. Power & Energy engineering deals with

5566-567: The Institution of Engineering and Technology (IET, formerly the IEE). Electrical engineers work in a very wide range of industries and the skills required are likewise variable. These range from circuit theory to the management skills of a project manager . The tools and equipment that an individual engineer may need are similarly variable, ranging from a simple voltmeter to sophisticated design and manufacturing software. Electricity has been

5687-864: The Neo-Assyrian period (911–609) BC. The Egyptian pyramids were built using three of the six simple machines, the inclined plane, the wedge, and the lever, to create structures like the Great Pyramid of Giza . The earliest civil engineer known by name is Imhotep . As one of the officials of the Pharaoh , Djosèr , he probably designed and supervised the construction of the Pyramid of Djoser (the Step Pyramid ) at Saqqara in Egypt around 2630–2611 BC. The earliest practical water-powered machines,

5808-547: The Newcomen steam engine . Smeaton designed the third Eddystone Lighthouse (1755–59) where he pioneered the use of ' hydraulic lime ' (a form of mortar which will set under water) and developed a technique involving dovetailed blocks of granite in the building of the lighthouse. He is important in the history, rediscovery of, and development of modern cement , because he identified the compositional requirements needed to obtain "hydraulicity" in lime; work which led ultimately to

5929-455: The U.S. Army Corps of Engineers . The word "engine" itself is of even older origin, ultimately deriving from the Latin ingenium ( c.  1250 ), meaning "innate quality, especially mental power, hence a clever invention." Later, as the design of civilian structures, such as bridges and buildings, matured as a technical discipline, the term civil engineering entered the lexicon as

6050-789: The Z3 , the world's first fully functional and programmable computer using electromechanical parts. In 1943, Tommy Flowers designed and built the Colossus , the world's first fully functional, electronic, digital and programmable computer. In 1946, the ENIAC (Electronic Numerical Integrator and Computer) of John Presper Eckert and John Mauchly followed, beginning the computing era. The arithmetic performance of these machines allowed engineers to develop completely new technologies and achieve new objectives. In 1948, Claude Shannon published "A Mathematical Theory of Communication" which mathematically describes

6171-547: The compression , error detection and error correction of digitally sampled signals. Signal processing is a very mathematically oriented and intensive area forming the core of digital signal processing and it is rapidly expanding with new applications in every field of electrical engineering such as communications, control, radar, audio engineering , broadcast engineering , power electronics, and biomedical engineering as many already existing analog systems are replaced with their digital counterparts. Analog signal processing

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6292-652: The doubling of transistors on an IC chip every two years, predicted by Gordon Moore in 1965. Silicon-gate MOS technology was developed by Federico Faggin at Fairchild in 1968. Since then, the MOSFET has been the basic building block of modern electronics. The mass-production of silicon MOSFETs and MOS integrated circuit chips, along with continuous MOSFET scaling miniaturization at an exponential pace (as predicted by Moore's law ), has since led to revolutionary changes in technology, economy, culture and thinking. The Apollo program which culminated in landing astronauts on

6413-451: The generation , transmission , and distribution of electricity as well as the design of a range of related devices. These include transformers , electric generators , electric motors , high voltage engineering, and power electronics . In many regions of the world, governments maintain an electrical network called a power grid that connects a variety of generators together with users of their energy. Users purchase electrical energy from

6534-484: The geometrical cross-section is different from the effective cross-section in which current actually flows, so the resistance is higher than expected. Similarly, if two conductors are near each other carrying AC current, their resistances increase due to the proximity effect . At commercial power frequency , these effects are significant for large conductors carrying large currents, such as busbars in an electrical substation , or large power cables carrying more than

6655-528: The inclined plane (ramp) were known since prehistoric times. The wheel , along with the wheel and axle mechanism, was invented in Mesopotamia (modern Iraq) during the 5th millennium BC. The lever mechanism first appeared around 5,000 years ago in the Near East , where it was used in a simple balance scale , and to move large objects in ancient Egyptian technology . The lever was also used in

6776-440: The service drop . Organic compounds such as octane, which has 8 carbon atoms and 18 hydrogen atoms, cannot conduct electricity. Oils are hydrocarbons, since carbon has the property of tetracovalency and forms covalent bonds with other elements such as hydrogen, since it does not lose or gain electrons, thus does not form ions. Covalent bonds are simply the sharing of electrons. Hence, there is no separation of ions when electricity

6897-566: The shadoof water-lifting device, the first crane machine, which appeared in Mesopotamia c.  3000 BC , and then in ancient Egyptian technology c.  2000 BC . The earliest evidence of pulleys date back to Mesopotamia in the early 2nd millennium BC, and ancient Egypt during the Twelfth Dynasty (1991–1802 BC). The screw , the last of the simple machines to be invented, first appeared in Mesopotamia during

7018-446: The transmission of information across a communication channel such as a coax cable , optical fiber or free space . Transmissions across free space require information to be encoded in a carrier signal to shift the information to a carrier frequency suitable for transmission; this is known as modulation . Popular analog modulation techniques include amplitude modulation and frequency modulation . The choice of modulation affects

7139-639: The water wheel and watermill , first appeared in the Persian Empire , in what are now Iraq and Iran, by the early 4th century BC. Kush developed the Sakia during the 4th century BC, which relied on animal power instead of human energy. Hafirs were developed as a type of reservoir in Kush to store and contain water as well as boost irrigation. Sappers were employed to build causeways during military campaigns. Kushite ancestors built speos during

7260-412: The 14th century when an engine'er (literally, one who builds or operates a siege engine ) referred to "a constructor of military engines". In this context, now obsolete, an "engine" referred to a military machine, i.e. , a mechanical contraption used in war (for example, a catapult ). Notable examples of the obsolete usage which have survived to the present day are military engineering corps, e.g. ,

7381-426: The 1800s included the experiments of Alessandro Volta , Michael Faraday , Georg Ohm and others and the invention of the electric telegraph in 1816 and the electric motor in 1872. The theoretical work of James Maxwell (see: Maxwell's equations ) and Heinrich Hertz in the late 19th century gave rise to the field of electronics . The later inventions of the vacuum tube and the transistor further accelerated

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7502-429: The 1850s had shown the relationship of different forms of electromagnetic radiation including the possibility of invisible airborne waves (later called "radio waves"). In his classic physics experiments of 1888, Heinrich Hertz proved Maxwell's theory by transmitting radio waves with a spark-gap transmitter , and detected them by using simple electrical devices. Other physicists experimented with these new waves and in

7623-603: The 36 licensed member institutions of the UK Engineering Council . New specialties sometimes combine with the traditional fields and form new branches – for example, Earth systems engineering and management involves a wide range of subject areas including engineering studies , environmental science , engineering ethics and philosophy of engineering . Aerospace engineering covers the design, development, manufacture and operational behaviour of aircraft , satellites and rockets . Marine engineering covers

7744-576: The 9th century. In 1206, Al-Jazari invented programmable automata / robots . He described four automaton musicians, including drummers operated by a programmable drum machine , where they could be made to play different rhythms and different drum patterns. Before the development of modern engineering, mathematics was used by artisans and craftsmen, such as millwrights , clockmakers , instrument makers and surveyors. Aside from these professions, universities were not believed to have had much practical significance to technology. A standard reference for

7865-546: The Antikythera mechanism, required sophisticated knowledge of differential gearing or epicyclic gearing , two key principles in machine theory that helped design the gear trains of the Industrial Revolution, and are widely used in fields such as robotics and automotive engineering . Ancient Chinese, Greek, Roman and Hunnic armies employed military machines and inventions such as artillery which

7986-484: The Bronze Age between 3700 and 3250 BC. Bloomeries and blast furnaces were also created during the 7th centuries BC in Kush. Ancient Greece developed machines in both civilian and military domains. The Antikythera mechanism , an early known mechanical analog computer , and the mechanical inventions of Archimedes , are examples of Greek mechanical engineering. Some of Archimedes' inventions, as well as

8107-656: The Moon with Apollo 11 in 1969 was enabled by NASA 's adoption of advances in semiconductor electronic technology , including MOSFETs in the Interplanetary Monitoring Platform (IMP) and silicon integrated circuit chips in the Apollo Guidance Computer (AGC). The development of MOS integrated circuit technology in the 1960s led to the invention of the microprocessor in the early 1970s. The first single-chip microprocessor

8228-578: The Royal Academy of Natural Sciences and Arts of Barcelona. Salva's electrolyte telegraph system was very innovative though it was greatly influenced by and based upon two discoveries made in Europe in 1800—Alessandro Volta's electric battery for generating an electric current and William Nicholson and Anthony Carlyle's electrolysis of water. Electrical telegraphy may be considered the first example of electrical engineering. Electrical engineering became

8349-654: The United States went to Josiah Willard Gibbs at Yale University in 1863; it was also the second PhD awarded in science in the U.S. Only a decade after the successful flights by the Wright brothers , there was extensive development of aeronautical engineering through development of military aircraft that were used in World War I . Meanwhile, research to provide fundamental background science continued by combining theoretical physics with experiments. Engineering

8470-554: The amplifier tube, called the triode . In 1920, Albert Hull developed the magnetron which would eventually lead to the development of the microwave oven in 1946 by Percy Spencer . In 1934, the British military began to make strides toward radar (which also uses the magnetron) under the direction of Dr Wimperis, culminating in the operation of the first radar station at Bawdsey in August 1936. In 1941, Konrad Zuse presented

8591-815: The applications of computer engineering. Photonics and optics deals with the generation, transmission, amplification, modulation, detection, and analysis of electromagnetic radiation . The application of optics deals with design of optical instruments such as lenses , microscopes , telescopes , and other equipment that uses the properties of electromagnetic radiation. Other prominent applications of optics include electro-optical sensors and measurement systems, lasers , fiber-optic communication systems, and optical disc systems (e.g. CD and DVD). Photonics builds heavily on optical technology, supplemented with modern developments such as optoelectronics (mostly involving semiconductors ), laser systems, optical amplifiers and novel materials (e.g. metamaterials ). Mechatronics

8712-409: The aviation pioneers around the start of the 20th century although the work of Sir George Cayley has recently been dated as being from the last decade of the 18th century. Early knowledge of aeronautical engineering was largely empirical with some concepts and skills imported from other branches of engineering. The first PhD in engineering (technically, applied science and engineering ) awarded in

8833-462: The conductor is made from (as described above) and the conductor's size. For a given material, conductors with a larger cross-sectional area have less resistance than conductors with a smaller cross-sectional area. For bare conductors, the ultimate limit is the point at which power lost to resistance causes the conductor to melt. Aside from fuses , most conductors in the real world are operated far below this limit, however. For example, household wiring

8954-413: The cost and performance of a system and these two factors must be balanced carefully by the engineer. Once the transmission characteristics of a system are determined, telecommunication engineers design the transmitters and receivers needed for such systems. These two are sometimes combined to form a two-way communication device known as a transceiver . A key consideration in the design of transmitters

9075-465: The curvature of the Earth. Marconi later transmitted the wireless signals across the Atlantic between Poldhu, Cornwall , and St. John's, Newfoundland , a distance of 2,100 miles (3,400 km). Millimetre wave communication was first investigated by Jagadish Chandra Bose during 1894–1896, when he reached an extremely high frequency of up to 60   GHz in his experiments. He also introduced

9196-499: The design of devices to measure physical quantities such as pressure , flow , and temperature. The design of such instruments requires a good understanding of physics that often extends beyond electromagnetic theory . For example, flight instruments measure variables such as wind speed and altitude to enable pilots the control of aircraft analytically. Similarly, thermocouples use the Peltier-Seebeck effect to measure

9317-559: The design of new hardware . Computer engineers may also work on a system's software. However, the design of complex software systems is often the domain of software engineering, which is usually considered a separate discipline. Desktop computers represent a tiny fraction of the devices a computer engineer might work on, as computer-like architectures are now found in a range of embedded devices including video game consoles and DVD players . Computer engineers are involved in many hardware and software aspects of computing. Robots are one of

9438-571: The design, development, manufacture and operational behaviour of watercraft and stationary structures like oil platforms and ports . Computer engineering (CE) is a branch of engineering that integrates several fields of computer science and electronic engineering required to develop computer hardware and software . Computer engineers usually have training in electronic engineering (or electrical engineering ), software design , and hardware-software integration instead of only software engineering or electronic engineering. Geological engineering

9559-575: The desired manner. To implement such controllers, electronics control engineers may use electronic circuits , digital signal processors , microcontrollers , and programmable logic controllers (PLCs). Control engineering has a wide range of applications from the flight and propulsion systems of commercial airliners to the cruise control present in many modern automobiles . It also plays an important role in industrial automation . Control engineers often use feedback when designing control systems . For example, in an automobile with cruise control

9680-418: The desired transport of electronic charge and control of current. The field of microelectronics involves a significant amount of chemistry and material science and requires the electronic engineer working in the field to have a very good working knowledge of the effects of quantum mechanics . Signal processing deals with the analysis and manipulation of signals . Signals can be either analog , in which case

9801-407: The development and large scale manufacturing of chemicals in new industrial plants. The role of the chemical engineer was the design of these chemical plants and processes. Aeronautical engineering deals with aircraft design process design while aerospace engineering is a more modern term that expands the reach of the discipline by including spacecraft design. Its origins can be traced back to

9922-418: The development of electronics to such an extent that electrical and electronics engineers currently outnumber their colleagues of any other engineering specialty. Chemical engineering developed in the late nineteenth century. Industrial scale manufacturing demanded new materials and new processes and by 1880 the need for large scale production of chemicals was such that a new industry was created, dedicated to

10043-504: The first Department of Electrical Engineering in the United States. In the same year, University College London founded the first chair of electrical engineering in Great Britain. Professor Mendell P. Weinbach at University of Missouri established the electrical engineering department in 1886. Afterwards, universities and institutes of technology gradually started to offer electrical engineering programs to their students all over

10164-421: The first commercial piston steam engine in 1712, was not known to have any scientific training. The application of steam-powered cast iron blowing cylinders for providing pressurized air for blast furnaces lead to a large increase in iron production in the late 18th century. The higher furnace temperatures made possible with steam-powered blast allowed for the use of more lime in blast furnaces , which enabled

10285-409: The first half of the 19th century. These included the use of gigs to guide the machining tool over the work and fixtures to hold the work in the proper position. Machine tools and machining techniques capable of producing interchangeable parts lead to large scale factory production by the late 19th century. The United States Census of 1850 listed the occupation of "engineer" for the first time with

10406-579: The future it is hoped the devices will help build tiny implantable medical devices and improve optical communication . In aerospace engineering and robotics , an example is the most recent electric propulsion and ion propulsion. Electrical engineers typically possess an academic degree with a major in electrical engineering, electronics engineering , electrical engineering technology , or electrical and electronic engineering. The same fundamental principles are taught in all programs, though emphasis may vary according to title. The length of study for such

10527-426: The geometry of the conductor and therefore its characteristic resistance. However, this effect is generally small, on the order of 10 . An increase in temperature will also increase the number of phonons generated within the material. A phonon is essentially a lattice vibration, or rather a small, harmonic kinetic movement of the atoms of the material. Much like the shaking of a pinball machine, phonons serve to disrupt

10648-532: The grid, avoiding the costly exercise of having to generate their own. Power engineers may work on the design and maintenance of the power grid as well as the power systems that connect to it. Such systems are called on-grid power systems and may supply the grid with additional power, draw power from the grid, or do both. Power engineers may also work on systems that do not connect to the grid, called off-grid power systems, which in some cases are preferable to on-grid systems. Telecommunications engineering focuses on

10769-456: The international standardization of the units volt , ampere , coulomb , ohm , farad , and henry . This was achieved at an international conference in Chicago in 1893. The publication of these standards formed the basis of future advances in standardization in various industries, and in many countries, the definitions were immediately recognized in relevant legislation. During these years,

10890-519: The invention of Portland cement . Applied science led to the development of the steam engine. The sequence of events began with the invention of the barometer and the measurement of atmospheric pressure by Evangelista Torricelli in 1643, demonstration of the force of atmospheric pressure by Otto von Guericke using the Magdeburg hemispheres in 1656, laboratory experiments by Denis Papin , who built experimental model steam engines and demonstrated

11011-457: The limits within which a viable object or system may be produced and operated. Electrical conductor In order for current to flow within a closed electrical circuit , one charged particle does not need to travel from the component producing the current (the current source ) to those consuming it (the loads ). Instead, the charged particle simply needs to nudge its neighbor a finite amount, who will nudge its neighbor, and on and on until

11132-466: The material it is made of, and on its dimensions. For a given material, the resistance is inversely proportional to the cross-sectional area. For example, a thick copper wire has lower resistance than an otherwise-identical thin copper wire. Also, for a given material, the resistance is proportional to the length; for example, a long copper wire has higher resistance than an otherwise-identical short copper wire. The resistance R and conductance G of

11253-443: The material, measured in ohm-metres (Ω·m). The resistivity and conductivity are proportionality constants, and therefore depend only on the material the wire is made of, not the geometry of the wire. Resistivity and conductivity are reciprocals : ρ = 1 / σ {\displaystyle \rho =1/\sigma } . Resistivity is a measure of the material's ability to oppose electric current. This formula

11374-445: The mid-to-late 1950s, the term radio engineering gradually gave way to the name electronic engineering . Before the invention of the integrated circuit in 1959, electronic circuits were constructed from discrete components that could be manipulated by humans. These discrete circuits consumed much space and power and were limited in speed, although they are still common in some applications. By contrast, integrated circuits packed

11495-509: The multi-disciplinary design issues of complex electrical and mechanical systems. The term mechatronics is typically used to refer to macroscopic systems but futurists have predicted the emergence of very small electromechanical devices. Already, such small devices, known as microelectromechanical systems (MEMS), are used in automobiles to tell airbags when to deploy, in digital projectors to create sharper images, and in inkjet printers to create nozzles for high definition printing. In

11616-518: The new Society of Telegraph Engineers (soon to be renamed the Institution of Electrical Engineers ) where he was regarded by other members as the first of their cohort. By the end of the 19th century, the world had been forever changed by the rapid communication made possible by the engineering development of land-lines, submarine cables , and, from about 1890, wireless telegraphy . Practical applications and advances in such fields created an increasing need for standardized units of measure . They led to

11737-523: The passage of information with uncertainty ( electrical noise ). The first working transistor was a point-contact transistor invented by John Bardeen and Walter Houser Brattain while working under William Shockley at the Bell Telephone Laboratories (BTL) in 1947. They then invented the bipolar junction transistor in 1948. While early junction transistors were relatively bulky devices that were difficult to manufacture on

11858-427: The path of electrons, causing them to scatter. This electron scattering will decrease the number of electron collisions and therefore will decrease the total amount of current transferred. Conduction materials include metals , electrolytes , superconductors , semiconductors , plasmas and some nonmetallic conductors such as graphite and conductive polymers . Copper has a high conductivity . Annealed copper

11979-479: The power to weight ratio of steam engines made practical steamboats and locomotives possible. New steel making processes, such as the Bessemer process and the open hearth furnace, ushered in an area of heavy engineering in the late 19th century. One of the most famous engineers of the mid-19th century was Isambard Kingdom Brunel , who built railroads, dockyards and steamships. The Industrial Revolution created

12100-401: The process developed devices for transmitting and detecting them. In 1895, Guglielmo Marconi began work on a way to adapt the known methods of transmitting and detecting these "Hertzian waves" into a purpose-built commercial wireless telegraphic system. Early on, he sent wireless signals over a distance of one and a half miles. In December 1901, he sent wireless waves that were not affected by

12221-434: The rise of engineering as a profession in the 18th century, the term became more narrowly applied to fields in which mathematics and science were applied to these ends. Similarly, in addition to military and civil engineering, the fields then known as the mechanic arts became incorporated into engineering. Canal building was an important engineering work during the early phases of the Industrial Revolution. John Smeaton

12342-426: The same with full cognizance of their design; or to forecast their behavior under specific operating conditions; all as respects an intended function, economics of operation and safety to life and property. Engineering has existed since ancient times, when humans devised inventions such as the wedge, lever, wheel and pulley, etc. The term engineering is derived from the word engineer , which itself dates back to

12463-425: The signal varies continuously according to the information, or digital , in which case the signal varies according to a series of discrete values representing the information. For analog signals, signal processing may involve the amplification and filtering of audio signals for audio equipment or the modulation and demodulation of signals for telecommunications. For digital signals, signal processing may involve

12584-408: The size is expressed in square millimetres. In North America, conductors are measured by American wire gauge for smaller ones, and circular mils for larger ones. The ampacity of a conductor, that is, the amount of current it can carry, is related to its electrical resistance: a lower-resistance conductor can carry a larger value of current. The resistance, in turn, is determined by the material

12705-470: The state of mechanical arts during the Renaissance is given in the mining engineering treatise De re metallica (1556), which also contains sections on geology, mining, and chemistry. De re metallica was the standard chemistry reference for the next 180 years. The science of classical mechanics , sometimes called Newtonian mechanics, formed the scientific basis of much of modern engineering. With

12826-410: The study of electricity was largely considered to be a subfield of physics since early electrical technology was considered electromechanical in nature. The Technische Universität Darmstadt founded the world's first department of electrical engineering in 1882 and introduced the first-degree course in electrical engineering in 1883. The first electrical engineering degree program in the United States

12947-442: The temperature difference between two points. Often instrumentation is not used by itself, but instead as the sensors of larger electrical systems. For example, a thermocouple might be used to help ensure a furnace's temperature remains constant. For this reason, instrumentation engineering is often viewed as the counterpart of control. Computer engineering deals with the design of computers and computer systems . This may involve

13068-475: The theoretical basis of alternating current engineering. The spread in the use of AC set off in the United States what has been called the war of the currents between a George Westinghouse backed AC system and a Thomas Edison backed DC power system, with AC being adopted as the overall standard. During the development of radio , many scientists and inventors contributed to radio technology and electronics. The mathematical work of James Clerk Maxwell during

13189-414: The transition from charcoal to coke . These innovations lowered the cost of iron, making horse railways and iron bridges practical. The puddling process , patented by Henry Cort in 1784 produced large scale quantities of wrought iron. Hot blast , patented by James Beaumont Neilson in 1828, greatly lowered the amount of fuel needed to smelt iron. With the development of the high pressure steam engine,

13310-420: The use of semiconductor junctions to detect radio waves, when he patented the radio crystal detector in 1901. In 1897, Karl Ferdinand Braun introduced the cathode-ray tube as part of an oscilloscope , a crucial enabling technology for electronic television . John Fleming invented the first radio tube, the diode , in 1904. Two years later, Robert von Lieben and Lee De Forest independently developed

13431-556: The use of transformers , developed rapidly in the 1880s and 1890s with transformer designs by Károly Zipernowsky , Ottó Bláthy and Miksa Déri (later called ZBD transformers), Lucien Gaulard , John Dixon Gibbs and William Stanley Jr. Practical AC motor designs including induction motors were independently invented by Galileo Ferraris and Nikola Tesla and further developed into a practical three-phase form by Mikhail Dolivo-Dobrovolsky and Charles Eugene Lancelot Brown . Charles Steinmetz and Oliver Heaviside contributed to

13552-587: The use of a piston, which he published in 1707. Edward Somerset, 2nd Marquess of Worcester published a book of 100 inventions containing a method for raising waters similar to a coffee percolator . Samuel Morland , a mathematician and inventor who worked on pumps, left notes at the Vauxhall Ordinance Office on a steam pump design that Thomas Savery read. In 1698 Savery built a steam pump called "The Miner's Friend". It employed both vacuum and pressure. Iron merchant Thomas Newcomen , who built

13673-484: The vehicle's speed is continuously monitored and fed back to the system which adjusts the motor's power output accordingly. Where there is regular feedback, control theory can be used to determine how the system responds to such feedback. Control engineers also work in robotics to design autonomous systems using control algorithms which interpret sensory feedback to control actuators that move robots such as autonomous vehicles , autonomous drones and others used in

13794-560: The world. During these decades the use of electrical engineering increased dramatically. In 1882, Thomas Edison switched on the world's first large-scale electric power network that provided 110 volts— direct current (DC)—to 59 customers on Manhattan Island in New York City. In 1884, Sir Charles Parsons invented the steam turbine allowing for more efficient electric power generation. Alternating current , with its ability to transmit power more efficiently over long distances via

13915-644: Was a steam jack driven by a steam turbine , described in 1551 by Taqi al-Din Muhammad ibn Ma'ruf in Ottoman Egypt . The cotton gin was invented in India by the 6th century AD, and the spinning wheel was invented in the Islamic world by the early 11th century, both of which were fundamental to the growth of the cotton industry . The spinning wheel was also a precursor to the spinning jenny , which

14036-522: Was a key development during the early Industrial Revolution in the 18th century. The earliest programmable machines were developed in the Muslim world. A music sequencer , a programmable musical instrument , was the earliest type of programmable machine. The first music sequencer was an automated flute player invented by the Banu Musa brothers, described in their Book of Ingenious Devices , in

14157-664: Was developed by the Greeks around the 4th century BC, the trireme , the ballista and the catapult . In the Middle Ages, the trebuchet was developed. The earliest practical wind-powered machines, the windmill and wind pump , first appeared in the Muslim world during the Islamic Golden Age , in what are now Iran, Afghanistan, and Pakistan, by the 9th century AD. The earliest practical steam-powered machine

14278-486: Was started at Massachusetts Institute of Technology (MIT) in the physics department under Professor Charles Cross, though it was Cornell University to produce the world's first electrical engineering graduates in 1885. The first course in electrical engineering was taught in 1883 in Cornell's Sibley College of Mechanical Engineering and Mechanic Arts . In about 1885, Cornell President Andrew Dickson White established

14399-455: Was the Intel 4004 , released in 1971. The Intel 4004 was designed and realized by Federico Faggin at Intel with his silicon-gate MOS technology, along with Intel's Marcian Hoff and Stanley Mazor and Busicom's Masatoshi Shima. The microprocessor led to the development of microcomputers and personal computers, and the microcomputer revolution . One of the properties of electricity is that it

14520-505: Was the first self-proclaimed civil engineer and is often regarded as the "father" of civil engineering. He was an English civil engineer responsible for the design of bridges, canals, harbors, and lighthouses. He was also a capable mechanical engineer and an eminent physicist . Using a model water wheel, Smeaton conducted experiments for seven years, determining ways to increase efficiency. Smeaton introduced iron axles and gears to water wheels. Smeaton also made mechanical improvements to

14641-466: Was the first truly compact transistor that could be miniaturised and mass-produced for a wide range of uses. It revolutionized the electronics industry , becoming the most widely used electronic device in the world. The MOSFET made it possible to build high-density integrated circuit chips. The earliest experimental MOS IC chip to be fabricated was built by Fred Heiman and Steven Hofstein at RCA Laboratories in 1962. MOS technology enabled Moore's law ,

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