What is electricity, actually?
Ever wonder what electricity is and how it works? This article will give an overview of electricity, what it is, what it is not, and will correct some of the many misconceptions about it.
Why it’s not a simple answer
Electricity can be somewhat of an elusive topic as it is viewed differently, depending on who you talk to. Many of the textbook definitions of electricity are muddy and contradictory – largely because we cannot observe electricity. That is to say, we cannot observe electrons, which are the fundamental ‘movers’ of electrical energy. Some books claim electricity is energy, some claim it is a quanta of charged particles; others claim it is the charge, but not the particle, and still, others say it is the movement of the charges that is the ‘electricity part’. Some texts, dictionaries included, say electricity is a force, others say it is created. Others say it can’t be created – it can only be transferred from another type of energy. Do you see the problem here? Most of these books are written by professionals in different industries, who all have a different frame of reference for what they believe electricity is.
We cannot see electricity, but we know it’s there because of its effect on the environment around us. For instance, if you turn on a lamp and it lights up the room, you know there’s electricity in your house even though you will not see the electrical current flowing on the wires in the walls. Many mistake the illumination of a light bulb to be electricity, when in reality illumination is simply a material glowing from heat that we’re observing – due to impeded electrons flowing through the material. This fundamental lack of observation has made for an immense amount of interpretation and guesswork over the years, which has allowed for some assumptions to manifest – and with them, some sloppy language.
The observation of “electricity”
There are many different types of relationships between the physical world and electricity all around us. Electricity is responsible for holding together physical matter. It’s also what allows lights to turn on, appliances to work, music to be sent from radio stations through the air and received in your car. Electricity is not something that can be created or destroyed because there exist, inherent in every atom, positively and negatively charged ‘electric’ particles. In this way, all matter that we can see or touch is built of electric particles. The very fabric of matter, and in fact reality, is electric in nature. Our brains use electrical signals as a way to build a picture and form a three-dimensional conceptual reality for us to exist within. Cosmic radiation, or light, made up of photons, is flying around us all day, every day – and most of it is invisible. These photons are electric packets of energy and information. Essentially it’s a cosmic wifi system that the universe exists within.
Inversely, on the smallest level of observable reality, for an atom to keep its ‘shape’, it requires an electrostatic bond. This means charged particles (electrons) are holding to each other to keep atoms locked in place. The attraction and repulsion of these charged particles are what makes matter coalesce into substances. In chemistry, we call these forces bonds. Electrostatic bonds are the type of force that keeps two atoms stuck together. The study of electrodynamics observes and measures these charges in motion.
One of the most useful ways of conceptualizing electricity is to view it as the utilization of the attraction and repulsion of charged particles in matter, to do some type of work. Electricity powers our devices and makes day-to-day life possible because of the movement of electrons in matter. Electrical energy cannot be created or destroyed, it simply transfers or transforms between other energetic bodies. We hear people say that we ‘generate’ electricity at utility power plants, so it makes people think they are creating electricity. But electricity already exists. What the utility company is doing, that they’re charging us for, is creating mechanical motion in a machine. This machine (a generator) spins, and this spinning is useful as a force. This spinning is what we call mechanical energy. If we were to put a tire on the spinning generator and attach it to a car, we’d have a vehicle that could move, or “do work”. But in electricity, we don’t care so much about the mechanical movement – only that it’s creating motion that is useful in transferring mechanical energy to an electrical circuit, and changing it into electrical energy. When we put conductors (wires) next to the spinning magnets in this generator, we observe a crazy phenomenon: the force of the spinning magnets can be carried down the wires, without the wires needing to move! This is because conductors have the ability to take in mechanical energy and transfer it to electrical energy. So the actual energy can be transferred without the motion needing to be.
Now don’t be misled, there is still motion occurring on the quantum level inside of a conductor. We just can’t observe it, so it appears that the motion is no longer happening. But be assured, the electrons inside of that conductor are vibrating back and forth dozens of times per second (Hertz) – in some circuits, hundreds, thousands (KiloHertz), and millions (GigaHertz) of times per second. The part most people don’t understand is that this movement of electrons is not itself, electricity. Electrons are matter, and have energy – we think. Again, we can’t observe electrons but physicists agree that they have mass, and therefore are matter. The movement of electrons through a conductor is called an electric current, and is a part of electricity – but it is not the whole picture. Electricity can still exist when charges are static, in the case of the electrostatic bonds mentioned above. So the movement of electrons as electrical current is only one part of what electric things can do.
The “PARTS” of electricity
Electricity, therefore, is best understood when broken down into its individual parts, then repackaged together and understood as a whole. Let’s look at all of the parts of what we call ‘electricity’, to see it from all sides.
Charged Particles
Electrons and protons inside of atoms each carry a certain amount of charge. A charge can be understood as a buildup of energy or pressure that either pushes out from a particle or pulls inward. We’ve deemed electrons as having a negative charge, and we typically draw an electron’s charges coming inward towards the particle. We also say that protons have a positive charge, and draw them with lines moving away from the particle. The charged particles are considered matter, as they have mass – so the charged particles by themselves are not electricity. What about the force that these charged particles exert, though? Is the buildup, or quantity of charge surrounding a particle, electricity? The answer is the same… sort of.
Neither charges nor charged particles, can exist without the other. It’s sort of like space-time. Without space, we cannot traverse time, and without time we cannot traverse space. Without the charged particle, there is no charge; and without the buildup of charge, there is no charged particle. So there are two sides to observing the same phenomenon. In other words, if one of them ‘is electricity,’ then so is the other.
Electric Fields
Between two charged particles there exists a space, or a field, where a force can be felt. This force is an electric force, a push or a pull experienced between two electric bodies. This force is not electricity itself; it’s just the property of electricity that causes electric objects to behave in a certain way when placed in a circuit.
Starting with electric fields, these can be created by an electrostatic field. This occurs because charged particles carry positive or negative electric charges, and in nature both like and unlike charge attract each other – for example, the opposite ends of a magnet are oppositely “magnetically charged,” so two magnets with opposite fields are drawn to each other, and two magnets with the same fields repel each other. This space between the magnets where the force is felt is what we call a magnetic field. This is exactly how two charged particles with the same sign interact. If we were to take two bundles of charged metal and place them on opposite sides of a wooden box, they would attract each other – and between them is where we would be able to measure the appearance of an electric field. Electric fields exist between electric charges, magnetic fields exist between magnetics.
This is all happening on the macro scale as individual electrons (negatively) and protons (positively) reach across space to find their opposing sign. Just as valuable though, are when similar charges interact with one another. When two electrons come toward each other, they repel because their electric charges are the same. This is called Coulomb’s law of electric charge. As you can see, electric fields are still only a part of the whole that is ‘electricity’.
Static vs Motion
We’ve briefly discussed the terms static, dynamic, and current in reference to electricity. Let’s now talk about them more in-depth so we can relate them to what electricity is as a whole. Static electricity is an electrical charge that builds up on a surface. Static electricity is a slightly misleading term, as it still deals with moving electrons. The electrical potential that exists on objects builds up, and for the most part, stays at rest until acted upon externally. It is caused by the separation of charge on surfaces that are not moving relative to one another. So something that is “charged” or “storing a charge” is just as electric as the thing when it disburses the charge. One example is the separation and build-up of charges by rubbing two materials together, or by the movement of electrons from one material to another. When you rub a balloon against your hair and your hair sticks to the balloon, you are seeing static electricity in action.
Dynamic electricity occurs when ions move within a liquid or gas, which causes the charge to flow through the material. This type of electric current is used in many industries for many different applications, including medical devices, semiconductors, and batteries. In a battery, we have an electrochemical cell that converts chemical energy into electrical energy. It consists of two electrodes: the cathode and the anode, which are separated by a liquid or gel called an electrolyte. When the external circuit is completed between these two electrodes through a load (e.g. a light bulb), electrons flow from one electrode to the other through the external electric circuit.
When you charge the battery, you need to apply an external voltage across the two plates. The external voltage creates currents through ion transfer between cathode and anode. There are moving electrons on one side of the atoms that also result in positive ions being moved from one atom to another. This internal motion of ions, and external motion of charges can be thought of as dynamic electrical current.
Electric current is generally a term used when referring to the movement of electrons through metal conductors. It is true that electric currents also exist when static electricity discharges, as well as when currents travel in dynamic chemical environments. ‘The movement of electrical charges’ is more of a correct description of the term. For electrical circuits, we use electric current to mean the movement of electrons through conductors. A good way to imagine this is to think about the flow of water in a river. A certain amount of flow is occurring over time. Gallons per minute, liters per second, etc. Electric current works on this same principle, only instead of using volume over time, it uses charge density (in coulombs per cubic meter) over time. The quantity of charges moving per second is what we refer to as amperes.
The movement of electrons into a large current can have quite a force behind it, especially once you increase electrical potential (voltage). At certain levels of current, metal can be melted together (in the case of welding), and even higher yet can vaporize metal (as occurs during an arc flash). The controlled movement of electrons through a load can be quite useful as well. When we put a load, such as a fan or a lightbulb, into a circuit, we force electric current to encounter impedance. Because of its opposition to current flow, we’re able to safely use the force to do work for us.
None of these three instances – static electricity, dynamic electricity, and electric current – are electricity. They are simply small, ‘zoomed-in’ observations of what electrically charged particles are doing in specific situationss. We’ve come a long way, but we still haven’t found true ‘electricity’ laying around anywhere. Let’s keep going.
Difference of Potential
The difference of electrical potential is what we call voltage. When two electrically charged objects are at the same potential, current cannot flow between them. The way we get electrical current to flow is by creating a difference of potential between the two objects, by which current can flow between them. One has to be positive, and the other has to be negative. If we think of water, we can use a water slide as our analogy. For water to flow we have to raise the slide – creating an up and a down, or a difference between two potentials. If we flatten the slide down to the ground, there is no longer an up and a down, so water will simply rest. It has nowhere to flow. This is how electrical charges work as well.
Inherent in every atom there exists a difference of potential, or a positive and negative, in the same space. Every atom can be described as a balancing act of the attractive force between positive and negative potentials. The protons in the nucleus have positive charges, while electrons orbiting around it have negative charges. When atoms attempt to react with one another, there will always be an electron from one atom that will try to bond with a proton from the other – however, this cannot happen because the electrons undergo something called the Heisenberg Uncertainty Principle which is theorized to be the reason electrons are repelled from the nucleus of all atoms. The negative electrons instead, balance out electrically in the field between the two atoms.
Is electricity, then, just the fundamental property of every atom – that voltage exists within everything? If so, that means everything in the material physical universe is electric. Ah, but here we go assuming things again. What about the non-material, or non-physical things that still act electrically, independent of charged particles in atoms?
We now introduce, the photon.
Electromagnetism
Before we dive off into photons, we need to introduce the topic of electromagnetism. Electromagnetism, simply put, is the study of the attraction and repulsion of electric charges. Many properties that exist within electric circuits are also seen in objects that are magnetic. William Whewell coined the term electromagnetism in 1853 when he wanted to describe the relationship between electricity and magnetism. He chose this term because it means “the magnetic force produced by an electric current”.
On a higher level, electromagnetism is one of the four fundamental forces in physics that bind our universe and physical reality. Along with gravity, and the strong and weak nuclear forces, electromagnetism governs how matter is held together. There are two types of electromagnetism that we’ll look at, the first of which involves our newly introduced photon. Ok, back to the regularly scheduled program – photon, you’re on!
Electromagnetic Radiation
One of the two types of electromagnetism that exist is electromagnetic radiation. What we mean is, using electricity and magnetism we can observe fields and/or particles radiating from an electromagnetic source. We can also use a receiver to collect and measure these waves and particles coming from a source. The easiest of these to understand is visible light.
When we start to discuss light, we really begin to muddy up the conversation. Light doesn’t behave like matter, because it is not matter. The fundamental particle of light is our new friend, the photon, and it is a carrier of energy. When a lightbulb turns on, electrons inside of the filament of the lightbulb become excited. The electrons vibrate faster, and this translates to higher energy. These electrons lose some of their energy when they collide with other atoms in the filament. Electromagnetic radiation is created as a byproduct, which allows for little packets of energy to eject from the filament and travel through space. These little packets are photons. But not all photons can be seen by eyes. Only those at a certain frequency of vibration.
We see photons that vibrate and exist within the visible spectrum of light, which is a very small part of the whole spectrum. There are photons vibrating at much higher and lower frequencies than our eyes can perceive, but exist with varying energies around us every day. Examples of these are ultraviolet (UV) photons from the sun, and microwave photons from your microwave. We can see the results of the photons doing something energetically, but we can’t see them within the visible spectrum of human sight.
Photons interact with electrons when they smash into an atom. Quantum mechanics states that this interaction causes electrons in the atom to jump from one energy level to another, releasing or absorbing the difference in potential energy between the two levels. Electrons are said to be ‘excited’ by the addition of a photon, or slightly energized. This is because an excited electron has stored energy in it. The typical behavior of an electron after being excited is to emit that extra energy as soon as it can as a lower frequency photon, which matches what we can see within our visible spectrum – for example, a photon that’s vibrating at the speed our eyes interpret as the color red.
For electrons to exist at higher energies, they must absorb photons that carry this energy. This process is called excitation, and when electrons become excited they sit on higher, unstable energy levels within an atom or molecule until the excess energy they have gained is given off as a photon. This photon has the same energy, but a lower frequency than it came in with, because some of the vibration has been absorbed by the interaction. This process is also sometimes referred to as fluorescence. The typical behaviors of an electron after being excited are either for the electron to sit on its new, higher level by spitting out photons at that higher frequency (fluorescence), or for it to lose enough energy so that it drops down into a lower state and then emits a photon with less energy.
Why then do we see different colors from different materials? The reason is that when electrons become excited within a material they emit photons at very specific frequencies which enable us to see those specific colored lights. For example, when an electron becomes excited within sodium chloride nitrogen (NaClN), it’s going to emit photons at a frequency of 589 nm, which is blue. When it gets excited within cadmium sulfide selenide (CdSeSe), the frequency that it’ll emit will be 459 nm – which is yellow-green.
This pattern holds true for all materials based on chemical structure. If we want to make something that glows red then we might use copper (II) sulfate pentahydrate [(CuSO4)2(H2O)) as the fluorescing medium, and if we want something that glows green then perhaps we would use copper oxide containing barium selenite (Ba,Cu)(SeO3).
So now we understand that electricity is more complicated than physical objects. Are electrons electricity, or are photons? We’re not there yet.
Electromagnetic Induction
Another type of electromagnetism is electromagnetic induction. Electromagnetic induction is the basis for all electrical generators, as well as transformers, motors, power lines, coils, and any object that uses electricity to store or translate energy or information. Electromagnetic induction happens when a magnetic field is placed near an electric circuit, or vice versa. This induces electric currents in any conductive object close to the piece with the magnetic field. This principle was discovered by André Ampere, a French mathematician who used it to build the first model electric motor. In honor of his discovery, the SI unit for measuring magnetic flux is named after him: the ampere, or as we field techs call it, the amp.
There are two types of electromagnetic fields: A changing electric field, and a changing magnetic field. Either type of field can induce the other, but you need some good conductive material for the induced electromagnetism to travel through. So electromagnetic induction happens in all kinds of metal objects – especially conducting wires – when there is a nearby magnetic field that changes with time.
Since we know that moving charges generate a magnetic field, it only stands to reason that when we make an electric current go back and forth in a wire, we should be able to generate a changing magnetic field near the wire, as well as an induced EMF — hence electromagnetic induction!
Electromotive Force
Another electrical term we come across often is EMF, or Electromotive Force. A measure of EMF is a measurement of how much work you can do with electricity – it’s the potential energy of one Coulomb (6.241509 x 1019 electrons) in a voltaic cell if it was moved a distance of one meter – or in other words, an ‘electron-volt’.
If we did an experiment with a piece of iron (Fe) and a piece of copper (Cu) as electrodes and connected them by ionized saltwater, they would have an EMF between them. The EMF created by the electrical potential that exists between the metals, would push charges to flow through the wire and complete the circuit. The strength of the EMF will depend on how many charges are flowing through the wire, therefore it can be measured by inserting a multimeter between two electrodes. This completes the circuit, allowing current to flow through the meter, which then reports a reading of how much current is flowing per second. If we decreased the impedance of the circuit or increased the voltage, there would be more electrons passed through the circuit so the multimeter would show more amperes of current flow.
So this begs the question… is EMF electricity? It’s definitely part of the whole, but it is not the whole on its own.
Summary
Now we have to take in all of those separate parts and view how they work together. Let’s combine everything we’ve learned and see if we can parse what exactly electricity is. We’ve seen that ‘electricity’ is a term that is used for a phenomenon that occurs in and around matter called protons and neutrons, as well as in energetic particles and fields such as protons. We can measure the electric fields around the charged particles and we can make inferences about the difference of potential between these charges. We can even put these charged particles in motion, and observe the resulting expanding and collapsing magnetic fields around a conductor. We see that electricity, through the electromotive force, can also propagate waves and radiate through air, as well as induce currents from one circuit to another. So, again we’re stuck with this question of “what is electricity?” The answer is that there isn’t a clear answer.
The problem with the understanding of electricity is that we don’t have a proper definition. Lots of books, including high school and college textbooks, give contradictory information. Some call electricity a quantity of charge, some call it an energy, some call it a force, some say it is a thing that radiates, some say it is the difference of potential that exists in every atom. These are all right, but they’re all also missing the forest for the trees.
Electricity is not one thing, rather the word ‘electricity’ equates to a collection of electric things. It is often incorrectly spoken about, depending on what the speaker means by ‘electric things”’. Some might consider it a silly waste of time, to get this in-depth with parsing the language of electric things; and they may be right. Very few people are having conversations about such observations, so I suppose it is those who care enough about gaining a deep understanding of the subject that seek resolve. We should consider what we’re saying when we say we “work with electricity” every day as electricians. What do we mean? Are we saying that we’re working with energy? I think most people come to this conclusion.
A New Definition
Perhaps a good definition of Electricity could be:
“The material and energetic properties of, and the interaction between, charged particles, and their fields, at rest and in motion.”
This covers the particles, their charges, their fields, their interactions, movement, and non-movement. This is a more complete definition of electricity. But if you want to bake it down to something even more simplistic, electricity is most often thought of as the result of the interaction between charged particles.
