Electricity is an ubiquitous phenomenon. It is now ingrained in the various facets, and activities of our daily lives, to the point where its existence, and influence is very much taken for granted, with nothing more than a modicum of appreciation, for the singular force that powers the technologies that serve as the foundations of modern-day society. So, what exactly is electricity?
Honestly, it’s a difficult question. In my opinion, one of the greatest delights of being a physicist, involves a deep admiration for the unknown, and an acknowledgment of my own lack of knowledge. It has motivated me to persevere, and strive hard to learn as much as I can about the world that we occupy, and its myriad mysteries.
Electricity is one such mystery.
If I were to teasingly paraphrase Master Kenobi’s words,
“Electricity is what gives technology its power. It’s an energy field…it surrounds us, and penetrates us. It binds the galaxy together.”
In a way, this is true (a more precise statement would substitute electromagnetism for electricity), as we find electricity everywhere: from the lightning overhead, to the crackling static sparks of warm laundry, and even the functional impulses of the human nervous system. Electricity powers our world, and our bodies.
In this article, I’ll try to illuminate, to my best effort, the nature of electricity, its origins, and its practical applications.
Off to Miletus
Science finds its origins in the experimental method, which in ancient times, largely concerned the observation, and analysis of the surrounding world. The Greeks were stalwarts of both ancient philosophy, and science, and among them lived a philosopher of high regard, named Thales of Miletus (624-546 B.C.).
Thales was one among the legendary Seven Sages of Greece, a title given by ancient Greek tradition, to seven early 600 B.C. philosophers, statesmen, and law-makers who were renowned for their wisdom throughout the centuries.
Now, while the Greeks didn’t fully understand electricity, they certainly were aware of its existence. Thales is considered to have been the first human to have studied electricity. He found that by rubbing amber, or fossilized tree resin, with fur, he was able to attract lightweight objects like dust, and straw. He also noticed that lodestone (a naturally magnetic material) attracted bits of iron (magnetism is a close friend of electricity, but much about that later.) The word electricity is coined from the Greek word elektron, which also means amber. Thales’ work involved the first experiments of electrostatics, the study of stationary electric charges or static electricity.
Centuries would pass until electricity would find a foothold in modern science, and engineering. During this transition, and particularly in the 1700s, electricity was conceptualized to be a fluid. Familiar names such as Luigi Galvani, who asserted electricity to be the source of animation or animal motion, William Gilbert, an amateur scientist, who repeated Thales’ experiments, and Ben Franklin, who proved that lightning is electric in nature, and is constituted of positive, and negative elements, are among the many personalities who helped the scientific community form a clearer picture on how electricity works.
In the end, it was a French scientist named Charles Augustin de Coulomb, who summed up the work of his peers, and through his experiments, formulated what is now popularly known as Coulomb’s Law.
Coulomb’s law states that like charges repel, and opposite charges attract, with a quantified electric force that is proportional to the product of the two charges, and inversely proportional to the square of the distance between them.
Despite all this progress, the fundamental nature of electricity still eluded the scientific community.
Enter the Atomic Theory
Matter, as we now know, is composed of atoms. An atom is in itself composed of subatomic particles such as protons, and neutrons, concentrated in a nucleus, and surrounded by orbiting electrons. (A particle physicist may offer a slightly different description, as we have now found that protons, and neutrons are also made of constituent particles called quarks.)
Scientists discovered the existence of electrons in the early 19th century. This discovery set the stage for the rise of subatomic theory, and the beginning of the modern era of electricity, followed immediately by a rush of advances in technology.
There are various types of materials, but in the world of electricity, there are two primary categories: electrical insulators, and electrical conductors. Electrical insulators are materials that don’t conduct electricity very well. Wood is a wonderful example of an electrical insulator. Material or matter interactions are predominated by the sharing or exchange of electrons. But insulating materials are very reluctant in sharing electrons. This is because the electrons in insulators are tightly bound to their atoms.
Conductors,as you may have guessed, allow for this interaction, as their electrons can detach from their atoms, and fly about freely. These loose or free electrons make it easy for electricity to flow through these materials, aptly confirming their namesake as electrical conductors. Most metals are conductors. The motion of electrons transmits electrical energy from one point to another.
This simple premise opens the gateway to the many applications of modern day electricity each of which was the answer to a fundamental question:
(1) How can we make electricity flow from one point to another? Generators
(2) How do we make electricity? Power plants
(3) How do we contain this electricity? Circuits
Electricity is the flow of electrons. A generator helps stimulate this flow, using a magnet! We’ve often observed how we can move paperclips, and small bits of metals about a surface using a magnet. This is the principle behind the working mechanism of a generator. The motion of the paper clip is in response to the motion of electrons induced by the magnetic field.
Electricity, and magnetism are equal proponents of the other, as by running electricity through a metal wire, one can form a magnetic field around the wire! Such observations are definitive of a link between electricity, and magnetism, which eventually culminated in the successful formulation of Maxwell’s Laws of Electromagnetism.
But for now, let’s focus on electricity! Ultimately, the generator is a device that uses a magnet near a wire or conducting material to create a steady flow of electrons, and is the foundation of a power plant where electricity is made!
Power is the rate of doing work. It is defined as the ratio of energy consumed per unit time. To cause a particular change in a system, a necessary amount of energy is required, along with a specified interval of time in which the change is allowed to occur.
In physics, it is common to confuse work with power but they are distinct quantities. Work is the net change in the state of a system. A person carrying a crate up a set of stairs does the same amount of work whether he runs or walks, but more power is required for running while carrying the crate up the stairs, as the work being done is accomplished in a shorter period of time.
Power plants make use of this concept. They work to provide electricity over a period of time. But to do so, a power plant requires a generator. Michael Faraday conceived an early form of a generator where coils of copper wire are rotated between the poles of a magnet to produce an electrical current. In order to rotate the disk, a crank was utilized. This would be similar to the motions of using a pencil sharpener.
These old fashioned pencil sharpeners consist of a wheel, an axle, and a wedge. The handle serves as the axle that turns a wheel that is attached to the gears inside the sharpener to sharpen the pencil.
Now, imagine using a similar apparatus to crank out electricity for a neighborhood! It isn’t practical or viable! We would have to put a lot of work over a long period of time to generate even a reasonable amount of electricity! We have a generator, but the challenge is to apply the technology in an efficient manner to provide mass outputs of electricity.
In order to convert the input of mechanical (of cranking the handle) energy to a viable output of electrical energy, power plants seek the help of mother nature. There are many sources of electrical energy from hydro-electrical energy, to wind energy etc. All these technologies function using a fundamentally similar approach towards a common goal of producing electricity in mass.
Falling water has often been used as an energy source in ancient farms to modern day dams, and hydro-electricity plants, that use the enormous kinetic energy (or moving energy) delivered by falling water to crank out electricity. Engineers begin by building a dam across a river to create a reservoir. This reservoir of water is allowed to flow through the dam wall along a narrow channel called a penstock. At the end of a penstock, there is a turbine, or a large propeller. The shaft from the turbine goes up into the generator. When water moves across the turbine, the propellers spin, causing the shaft to rotate which in turn causes the copper coils of the generator to rotate. As these copper coils spin about the magnets, electricity is produced. Power lines carry this electricity from the plant to homes, and distant areas. Et voilà!
Now, while we have been successful in using a generator to “generate” electricity, there must be a means to contain this system of moving electrons. The answer to this involves the use of electrical circuits!
An electrical circuit helps monitor the flow of electricity. A simple circuit would look like this:
Circuits are pretty much analogous to subway maps. The more complicated the circuit, the more complicated the map. During my early years in Edmonton, I felt quite confident about my ability to get around the city, using the LRT (Light Rail Transit). This was partly due to how simplified the system was,
I remember proudly mentioning to Leina, my partner, that if I were to ever travel to Japan, I should not have a problem finding my way about the city, only for her to show me the Tokyo subway map, and challenging me to find a particular route:
My answer speaks for itself. But, just as we gain familiarity with our knowledge of our daily routes to work/school through the frequent use of public transport, by understanding the central principles of circuit theory (which sometimes, depending on how deep you want to go in the field, may involve a good undergraduate degree in electronics or so), one may eventually find their way about a circuit board like this,
Now, what does this all have to do with electricity? Circuits are necessary to monitor, and regulate electricity. No matter the source of electricity, be it a battery, a fuel cell, or a solar panel, the source of electricity generally has two terminals, a positive, and a negative terminal.
With reference to the simple circuit shown at the beginning of this section, electrons are pushed out of the negative terminal at a certain voltage (think of it as a force/pressure used to push the electrons, similar to how we may use a pump to push water out of a pipe). The electrons then flow from the negative terminal to the positive terminal through a conductor of choice (like copper wires). These wires form a closed path from the negative to the positive terminal, forming a circuit. A load, such as a light bulb, in the middle of the circuit may use the electricity flowing through the wire as a power source to generate light. While electrical circuits can get exceedingly complex, these basic principles of electron motion from the source generator, through a load, and back remain the same.
This concludes our discussion. Generators are the core mechanisms involved in making electricity, and are housed in power plants, which distribute the output electrical power to homes, and businesses, via power lines, and electrical circuits.
So what’s the point of all of this?
The point is…electricity is awesome!
My Masters thesis focuses on a simple circuit involving what is called a Single Dielectric Barrier Discharge (SDBD) Plasma Actuator. While I could write a book (which I have indeed, namely, my thesis) on the device, and its mechanisms, a simple description should be good for now.
An actuator is a device that converts an electrical input to produce a mechanical output (like the human body, neural “electrical” impulses from our brain, translate to our mechanical actions.) The SDBD plasma actuator does the same but does so using a medium known as a plasma, which is basically a soup of charged particles. Placing this device on an airplane wing, and turning it on, helps modify the airflow over the wing, reducing turbulence, and drag, while enhancing lift.
What’s this drag? For example, when you’re in a car, and you reach out the window, you can feel the force of the air against your open palm. This force is often referred to as the “drag” that your hand feels as air flows past it. It’s the same as when you walk through water, you feel its resistance, making your collective motions slower.
Airplanes are no different, feeling this frictional drag as they move through the atmosphere. The SDBD plasma actuator helps nullify this drag to a certain extent, aiding in the airplane’s motion through the air. But, in order to get the device to work in the first place, we need an electrical current! The SDBD plasma actuator is a Micro-Electro-Mechanical (MEM) System. Electricity is practically everywhere!
My goals for this review had been to talk about this physical force that is the primary benefactor of our daily lives, and a central principle behind the future of a technologically advanced human civilization. I hope I haven’t left anyone behind in the explanations provided above. I’ve tried my best to make the discussion concise, and enjoyable for those with, and without a scientific background. I hope everyone enjoyed reading this article!
- “Electricity.” Britannica Encyclopaedia. August 22, 2016 https://www.britannica.com/science/electricity
- Young, Hugh D., Freedman, Roger A., Ford, Lewis. University Physics. 2008.
- Gundersen, P. Erik. The Handy Physics Answer Book. Visible Ink Press. 2003.