The Busy 19th Century#

Things really kicked into high gear in the 1800s. This century saw a lot of fundamental discoveries that built the foundation for everything we do today.

• Hans Christian Ørsted: In 1820, he found that an electric current creates a magnetic field around it – you could see it make a compass needle move. This was a big link between electricity and magnetism.
• William Sturgeon: Building on that, he invented the electromagnet in 1825. This meant you could create magnetism with electricity and turn it on or off.
• Joseph Henry and Edward Davy: They invented the electrical relay in 1835, which is essentially an electric switch controlled by another electric current. Super important for things like telegraphs.
• Georg Ohm: In 1827, he figured out the mathematical relationship between how much current flows through a wire and the voltage pushing it. This is Ohm’s Law, a cornerstone of circuit analysis.
• Michael Faraday: He discovered electromagnetic induction in 1831. This is the principle behind electric generators and transformers – how you can create an electric current by changing a magnetic field.
• James Clerk Maxwell: The rockstar physicist who, in 1873, pulled all these ideas together into a single, elegant theory of electricity and magnetism with his famous equations. This unified understanding was key.

Early electrical engineering work was largely about communication. In 1782, Georges-Louis Le Sage showed off an electric telegraph system using 24 wires, one for each letter. It connected two rooms and used static electricity to move gold leaves. Francisco Salva Campillo also worked on electrostatic telegraphs and later an electrolytic one in the early 1800s, influenced by Volta’s battery and the idea of using electricity to split water.

These early telegraph systems, even though they seem simple now, were the first real examples of applying electrical principles to build something practical – essentially, the first electrical engineering. The need for engineers grew as a worldwide electric telegraph network was built. This led to the first professional groups for electrical engineers popping up in the UK and the US in the later 1800s. Francis Ronalds, who built a telegraph system in 1816, was seen as one of the earliest pioneers by these groups. By the late 1800s, telegraph lines crisscrossed continents and even went under the oceans, and wireless telegraphy (radio) was starting around 1890. This fast communication completely changed the world.

With all these new electrical inventions and systems, people needed a consistent way to measure electrical stuff. This led to international agreements on standard units like the volt (for voltage), ampere (for current), coulomb (for charge), ohm (for resistance), farad (for capacitance), and henry (for inductance) at a conference in Chicago in 1893. These standards were so important they were quickly written into laws in many countries and paved the way for future developments.

In the beginning, studying electricity was often part of physics because the early electrical devices often combined electrical and mechanical parts. But as the field grew, specific educational programs started. The Technische Universität Darmstadt in Germany started the first electrical engineering department in the world in 1882 and offered the first degree in 1883. In the US, MIT had an electrical engineering program within its physics department around the same time, but Cornell University is credited with graduating the first electrical engineers in 1885. Cornell also set up the first dedicated electrical engineering department in the US around 1885, the same year University College London got its first professor of electrical engineering. Other universities followed suit, offering specific degrees in the field.

The use of electrical engineering really exploded in these years, especially with electric power. In 1882, Thomas Edison got the world’s first large power network going in New York City, providing 110 volts of direct current (DC) power. Around the same time, Sir Charles Parsons invented the steam turbine, making power generation much more efficient. Then came alternating current (AC). AC had a big advantage: you could easily change its voltage using transformers, making it much more efficient to send power over long distances. AC technology developed fast in the 1880s and 90s with inventions by people like Károly Zipernowsky, Ottó Bláthy, Miksa Déri (the ZBD transformer), Lucien Gaulard, John Dixon Gibbs, and William Stanley Jr. Practical AC motors, like induction motors, were invented independently by Galileo Ferraris and Nikola Tesla, and improved into a three-phase system by Mikhail Dolivo-Dobrovolsky and Charles Eugene Lancelot Brown. People like Charles Steinmetz and Oliver Heaviside worked out the complex math needed for AC systems. This led to a famous “war of the currents” in the US between Edison’s DC system and the AC system backed by George Westinghouse. AC eventually won out as the standard for power distribution.

The Early 20th Century and the Rise of Electronics#

The early 1900s saw huge progress, especially in radio and early electronics. James Clerk Maxwell’s work from the 1850s had already suggested that invisible waves carrying energy could exist (what we now call radio waves). Heinrich Hertz proved this in 1888 by creating and detecting these waves using sparks and simple electrical tools.

Radio Waves: These are a type of electromagnetic radiation, like light or X-rays, but with much lower frequencies. They can travel through the air and are used for communication, broadcasting, radar, and more.

Many scientists then started experimenting with how to transmit and receive these waves. Guglielmo Marconi is famous for turning this into a practical wireless telegraph system starting in 1895. He quickly sent signals over a mile, then across the Atlantic Ocean by 1901 – a massive achievement at the time.

Interestingly, millimetre waves (a much higher frequency type of radio wave) were first explored by Jagadish Chandra Bose around 1894-1896, reaching frequencies up to 60 GHz in his lab. He also patented the radio crystal detector in 1901, using semiconductor junctions to detect radio waves, an early step towards solid-state electronics.

Other key inventions followed:

• Karl Ferdinand Braun: Introduced the cathode-ray tube (CRT) in 1897, which became vital for oscilloscopes (tools to see electrical signals) and early televisions.
• John Fleming: Invented the first vacuum tube used in radio, the diode, in 1904.
• Robert von Lieben and Lee De Forest: Independently developed the triode (an amplifier tube) around 1906, which could boost weak electrical signals.

During the Second World War, electrical engineering played a massive role, especially in radar and computing. Albert Hull developed the magnetron in 1920, a powerful vacuum tube. The British military used it to make big steps in radar development in the 1930s, setting up the first radar station in 1936. The magnetron later led to the invention of the microwave oven by Percy Spencer in 1946!

The war also pushed computing forward. Konrad Zuse in 1941 built the Z3, the first working, programmable computer using electrical relays (electromechanical parts). Then, Tommy Flowers in 1943 created the Colossus, the world’s first truly electronic, digital, programmable computer. In 1946, the ENIAC followed. These early computers, built by engineers, were much faster at calculations than anything before, allowing engineers to tackle tougher design problems and create new technologies.

In 1948, Claude Shannon published his groundbreaking work, “A Mathematical Theory of Communication,” which provided a mathematical way to think about sending information, including how to deal with electrical noise interfering with signals. This became the foundation of modern communication theory.

The Era of Solid-State Electronics#

One of the biggest shifts came with solid-state electronics, replacing bulky, power-hungry vacuum tubes with smaller, more reliable devices made from semiconductor materials.

Semiconductor: A material, like silicon or germanium, that conducts electricity better than an insulator but not as well as a pure conductor. Their electrical properties can be controlled, making them ideal for switches and amplifiers.

• The Transistor: The first working transistor was a point-contact type invented by John Bardeen and Walter Houser Brattain at Bell Telephone Laboratories (BTL) in 1947, under the direction of William Shockley. Shockley himself later invented the bipolar junction transistor in 1948. While early transistors were a bit tricky to make in large numbers, they were a huge step towards making electronics smaller.

• Integrated Circuits (ICs): The next big leap was putting multiple components onto a single piece of semiconductor material. Jack Kilby at Texas Instruments invented the hybrid integrated circuit in 1958, and Robert Noyce at Fairchild Semiconductor invented the monolithic integrated circuit chip in 1959. This meant circuits could be built on a tiny chip instead of wiring together many separate parts.

• The MOSFET: Arguably the most important invention in modern electronics was the MOSFET (Metal–Oxide–Semiconductor Field-Effect Transistor) by Mohamed Atalla and Dawon Kahng at BTL in 1959.

  MOSFET: This is a type of transistor that uses a voltage applied to a gate terminal to control the flow of current between two other terminals (source and drain). Its key advantage is that it uses very little power when switching between on and off states, making it perfect for digital circuits.

The MOSFET was the first transistor that was truly easy to shrink down and mass-produce. It completely changed the electronics industry and is now the most common electronic device on Earth.

The invention of the MOSFET made it possible to put many transistors onto a single chip, creating high-density integrated circuits. Fred Heiman and Steven Hofstein at RCA Laboratories made an early experimental MOS IC in 1962. This technology allowed for Moore’s Law to become a reality – the prediction made by Gordon Moore in 1965 that the number of transistors on an IC would roughly double every two years. Federico Faggin developed the silicon-gate MOS technology at Fairchild in 1968, which improved performance and reliability. Since then, the MOSFET has been the basic building block for almost all modern electronics. The ability to make billions of these tiny, cheap transistors on chips, and keep shrinking them (following Moore’s Law), has led to massive changes in technology, the economy, and our daily lives.

Think about the Apollo program that put humans on the moon in 1969. That depended heavily on advances in semiconductor electronics, including MOSFETs used in things like the Interplanetary Monitoring Platform and silicon ICs in the Apollo Guidance Computer that navigated the spacecraft.

The development of MOS integrated circuits in the 1960s directly led to the invention of the microprocessor in the early 1970s.

Microprocessor: This is basically a complete computer processor built onto a single integrated circuit chip. It contains the central processing unit (CPU) that performs calculations and logic operations.

The first single-chip microprocessor was the Intel 4004, released in 1971. It was designed and built by Federico Faggin using his silicon-gate MOS tech, along with Intel’s Marcian Hoff and Stanley Mazor, and Busicom’s Masatoshi Shima. The microprocessor powered the development of small computers (microcomputers) and eventually the personal computers we use today, kicking off the “microcomputer revolution.”

Power and Energy Engineering#

This area is all about getting electricity from where it’s made to where it’s used. Power engineers work on designing systems for generating, transmitting (sending it over long distances), and distributing electricity (getting it to your house or factory). They also design equipment like:

Transformers: Devices that change the voltage of AC electricity. Essential for sending power efficiently over long distances at high voltage and then lowering it to a safe level for use.

Electric Generators: Machines that convert other forms of energy (like mechanical energy from a turbine, or light energy in solar cells) into electrical energy.

Electric Motors: Devices that convert electrical energy into mechanical energy to make things move.

High Voltage Engineering: Dealing with the challenges and safety involved in working with very high electrical voltages, like those on transmission lines.

Power Electronics: Using electronic circuits and components (like transistors and diodes) to control and convert electrical power efficiently, used in things like electric car chargers and solar power converters.

In many places, there’s a large network called a power grid that connects power plants to customers. Power engineers design and keep this grid running. They also work on the systems that connect to the grid, called “on-grid” systems, which might either get power from the grid, send power back to it (like solar panels on a roof), or do both. Some power engineers design “off-grid” systems for places far from the main grid or for applications where being independent is important (like backup power systems or remote cabins).

Telecommunications Engineering#

Telecommunications: This field focuses on the technical aspects of sending information over distances using electrical or electromagnetic signals. Think phones, internet, radio, TV, satellite communication.

Telecommunications engineers figure out how to send information (voice, data, video) through different pathways, like copper wires, fiber optic cables (using light!), or through the air wirelessly. When sending signals through the air, the information needs to be put onto a “carrier signal” at a specific frequency suitable for transmission. This process is called modulation. Common ways to do this for older analog signals are:

Amplitude Modulation (AM): Changing the strength (amplitude) of the carrier wave according to the information signal.

Frequency Modulation (FM): Changing the frequency of the carrier wave according to the information signal.

Choosing the right modulation method is a big part of the job, balancing things like how much data you can send and how much the system costs. After figuring out the transmission method, these engineers design the equipment that sends (transmitters) and receives (receivers) the signals. Often, these are combined into a single device called a transceiver (like in your phone). A key challenge is making sure the signal is strong enough when it reaches the receiver. If the signal is too weak, static or noise can mess up the information.

Control Engineering#

This area is about making things behave the way you want them to. Control engineers create mathematical models of systems that change over time (dynamic systems) and then design “controllers” to make those systems follow specific commands or stay stable. The systems they work with are incredibly diverse, from airplanes to cars to industrial robots.

To build these controllers, they use various electronic components and systems like electronic circuits, digital signal processors (DSP), microcontrollers (small computers on a chip), and programmable logic controllers (PLCs) used in factories. Control engineering is crucial for things like:

• Aircraft flight control: Making sure planes fly smoothly and stay on course.
• Cruise control in cars: Keeping your car at a set speed without you constantly pressing the pedal.
• Industrial Automation: Making robots and machines in factories perform tasks automatically and precisely.

A core concept in control engineering is feedback. Imagine your car’s cruise control: it constantly checks your current speed (feedback) and adjusts the engine power to either speed up or slow down to match your desired speed. Control theory helps engineers predict how a system will react when this kind of feedback is used and design the controller to make it stable and perform well.

Control engineers also work heavily in robotics, designing the brains and algorithms that allow robots to move, sense their surroundings, and make decisions autonomously, like in self-driving cars or industrial robots that pick and place objects.

Electronics Engineering#

This is perhaps what many people first think of when they hear “electrical engineering,” though it’s a specific subfield. It’s all about designing and testing circuits made of electronic components.

Electronic Circuits: Networks of components like resistors, capacitors, inductors, diodes, and transistors connected together to perform a specific function, like filtering a signal, amplifying it, or performing logic operations.

A classic example is the tuning circuit in an old radio, which uses components like inductors and capacitors to pick out only the signal from the station you want to listen to and ignore others.

Before World War II, this field was often called “radio engineering” and focused mainly on communication (radio, telegraph) and early radar and television. After the war, as consumer electronics like modern TVs, audio systems, and early computers started appearing, the field expanded a lot. By the late 1950s, “electronic engineering” became the more common term.

In the old days, circuits were built using separate, individual components connected by wires. These “discrete” circuits worked, but they were big, used a lot of power, and weren’t very fast. The invention of the integrated circuit (IC) changed everything in 1959. Suddenly, millions of tiny components, mostly transistors, could be packed onto a small silicon chip. This miniaturization and increased speed made powerful computers and all the other electronic gadgets we rely on today possible.

Microelectronics and Nanoelectronics#

These fields dive into the world of the very small components used in integrated circuits.

Microelectronics: The design and manufacturing of extremely small electronic circuits and components, typically for use in integrated circuits.

Nanoelectronics: The further scaling down of electronic devices to the nanometer (billionth of a meter) level.

Microelectronic engineers design and create tiny components like semiconductor transistors on wafers of materials like silicon. For higher-speed circuits, they might use different semiconductor materials like gallium arsenide. Making these tiny parts involves complex chemical processes on the semiconductor material to control how electricity flows. This field requires engineers to understand chemistry and materials science well, and even needs some knowledge of quantum mechanics because at such small scales, the behavior of electrons is affected by quantum effects.

Modern electronic devices already use components in the nanometer range. Technology below 100 nanometers became standard around 2002, and today’s leading-edge chips have features just a few nanometers across.

Signal Processing#

Signal Processing: This area deals with analyzing, modifying, and interpreting signals. Signals can be anything that carries information, like sound waves, radio waves, voltages in a circuit, or even images.

Signals come in two main types:

Analog Signals: These vary smoothly and continuously, like the voltage changing from a microphone picking up sound waves.

Digital Signals: These represent information using a series of distinct, separate values, like the ones and zeros a computer uses. Analog signals are often converted to digital for processing.

For analog signals, signal processing might involve making a sound louder (amplification) or removing unwanted parts (filtering) in audio equipment. In telecommunications, it involves modulation (putting information onto a carrier wave) and demodulation (getting the information back off the carrier wave).

For digital signals, processing involves things like compressing data (making files smaller), detecting errors that might have occurred during transmission or storage, and correcting those errors.

Signal processing is a very mathematical field. Digital Signal Processing (DSP) is a core part of it and is growing fast because many older analog systems are being replaced with digital ones. DSP is used everywhere: in communications, control systems, radar, audio equipment, broadcasting, power electronics, and even medical devices.

You’ll find DSP chips (processors specifically designed for signal processing tasks) in tons of gadgets: digital TVs, radios, smartphones, MP3 players, cameras, car control systems, noise-canceling headphones, and much more. They handle things like cleaning up noise, recognizing or generating speech, handling digital audio/video, sending/receiving data wirelessly, figuring out GPS locations, and processing images.

Instrumentation Engineering#

Instrumentation Engineering: This is about designing devices and systems that measure physical stuff, like how hot something is (temperature), how fast something is flowing (flow), how much force is being applied (pressure), or how high something is (altitude).

Designing these measurement tools often needs a deep understanding of physics beyond just electricity and magnetism. For example, in an airplane cockpit, instruments measure things like airspeed and altitude so the pilot knows what the aircraft is doing. Thermocouples, which measure temperature difference, work based on a physics effect involving dissimilar metals (the Peltier-Seebeck effect).

Often, these instruments aren’t used by themselves but are part of larger systems as sensors. A thermocouple measuring furnace temperature might send that reading to a control system that turns the heat up or down. Because of this, instrumentation engineering often works closely with control engineering – the instruments provide the feedback that the control system uses.

Computer Engineering#

Computer Engineering: This discipline sits at the intersection of electrical engineering and computer science. It focuses on designing and building computers and computer systems, including both the hardware and sometimes the low-level software that makes the hardware work.

Computer engineers might design new computer processors, memory chips, circuit boards, or entire computer systems. While designing complex software is usually the job of software engineers, computer engineers often work on the software that directly interacts with hardware, like operating systems or embedded software. Computers aren’t just desktops and laptops anymore; computer engineering principles are used in the small computer-like systems found inside things like video game consoles, DVD players, smart appliances, and vehicles. Robots are a great example of a field where computer engineers work on both the electrical/mechanical hardware and the software that controls them.

Photonics and Optics#

Photonics: Deals with generating, controlling, and detecting light (photons), especially when used to transmit or process information.

Optics: A broader field concerned with the behavior and properties of light, including the design of instruments like lenses and telescopes.

These fields involve applying electrical engineering principles to light and other electromagnetic radiation. Photonics engineers work on devices and systems that use light, often combining optics with electronics (optoelectronics), particularly using semiconductors that can emit or detect light, or change its properties. Examples include:

• Lasers: Devices that produce highly focused, single-color light.
• Fiber-optic communication: Sending information over long distances using light pulses traveling through thin glass fibers – the backbone of the modern internet.
• Optical disc systems: Technologies like CDs and DVDs that use lasers to read and write data.
• Electro-optical sensors: Devices that use light to measure things or sense the environment.

Photonics builds on traditional optics but incorporates modern developments like semiconductor devices that interact with light, optical amplifiers (to boost light signals), and new materials designed to manipulate light in unique ways.

Mechatronics#

Mechatronics: An engineering field that combines mechanical engineering, electrical engineering, control engineering, and computer engineering to design and build integrated systems.

These combined systems are often called electromechanical systems. They are everywhere! Think about the automated machines in factories, the complex systems that control the temperature and air in buildings (HVAC), or the various electronic and mechanical parts working together in cars and airplanes.

While mechatronics often deals with larger systems, there’s also work on very tiny versions.

Microelectromechanical Systems (MEMS): Extremely small devices that combine mechanical and electrical components, often built using techniques similar to those for making integrated circuits.

MEMS are already used in things like sensors that tell airbags in cars when to inflate, tiny mirrors in digital projectors, and the incredibly small nozzles in inkjet printers. Looking ahead, MEMS and even smaller devices (sometimes called NEMS - Nanoelectromechanical Systems) are hoped to be useful for building tiny medical implants or improving communications.

Other related areas where electrical engineers contribute include electric propulsion systems for spacecraft (like ion thrusters) and robotics.