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Oct 23, 2023

What is the electromagnetic force?

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The electromagnetic force is one of the bedrock forces of nature and is easily the most important one to our modern world, even as most of us probably take it for granted.

As one of the four fundamental forces in the standard model, it's been at the center of scientific study for centuries, with even the ancients understanding that effects like static electricity were part of something bigger. It is a force that is all around us and is involved in a wide range of everyday phenomena, from the movement of electrons in wires to the behavior of magnets to the very light we see. Understanding the properties of this force is crucial for understanding everything from the behavior of subatomic particles to the design of electronic devices.

From the smallest subatomic particles to the largest structures in the universe, the electromagnetic force plays a vital role in shaping the world around us. By understanding this force more deeply, we can gain insights into the behavior of matter and energy that can help us to better understand the world and develop new technologies that can benefit us all.

The electromagnetic force is one of the four fundamental forces of nature, along with the strong nuclear force, the weak nuclear force, and gravity. It is responsible for the interaction between electrically charged particles, such as protons, electrons, and ions.

The importance of the electromagnetic force in physics can't be understated because it plays a role in virtually all of the phenomena that we observe in the world around us. It is responsible for the behavior of electric and magnetic fields, which are present in everything from lightning strikes to the operation of motors and generators.

Additionally, the electromagnetic force is responsible for the behavior of light and other forms of electromagnetic radiation, such as radio waves, microwaves, and X-rays.

At the subatomic level, the electromagnetic force is responsible for the behavior of charged particles within atoms and molecules. This force determines the structure of atoms and the chemical properties of elements, allowing for the formation of chemical bonds that hold molecules together.

Without the electromagnetic force, it would be impossible for molecules to form, and the complex chemistry that is necessary for life as we know it would not be possible.

One of the most significant applications of the electromagnetic force is in electronics and communications technology. By manipulating electric and magnetic fields, we can create and control the flow of electrons, allowing us to create circuits and devices that perform complex computations and transmit information over long distances. From cell phones to satellites, the electromagnetic force plays a vital role in our modern technological infrastructure.

The electromagnetic force also plays a crucial role in many other areas of physics, including particle physics, astrophysics, and cosmology. It is responsible for the behavior of charged particles in the presence of magnetic fields, which is important for understanding phenomena such as the aurora borealis, and for the study of high-energy particles in particle accelerators.

In short, it's pretty much everywhere and involved, somehow, in just about everything we do.

Fermilab

The evidence for the electromagnetic force is vast and has been accumulated over centuries of scientific inquiry. Some of the earliest evidence for the electromagnetic force can be traced back to the ancient Greeks, who observed that rubbing certain materials together could create static electricity.

This observation was later studied and expanded upon by scientists like Benjamin Franklin, who conducted experiments with electric charges and created the concept of positive and negative charges.

Another key piece of evidence for the electromagnetic force is the behavior of charged particles in the presence of an electric or magnetic field. For example, electrically charged particles can be accelerated by an electric field, while magnetically charged particles (i.e., those with a magnetic moment) can be deflected by a magnetic field. The behavior of these particles is consistent with the predictions of electromagnetic theory.

Additionally, the electromagnetic force has been directly observed and studied through experiments involving electromagnetism, such as the use of magnetic fields in particle accelerators to study the behavior of subatomic particles. The electromagnetic force is also responsible for the phenomenon of electromagnetic radiation, including visible light, X-rays, and radio waves, which can be observed and measured through a variety of experimental methods.

Royal Institution of London

It is impossible to say who "discovered" the electromagnetic force, as it is a fundamental force that has always existed, very obviously so, in nature.

However, the study of electricity and magnetism, which are the two phenomena that make up the electromagnetic force, dates back to ancient times. The ancient Greeks were aware of static electricity, and the Chinese military was using magnetic compasses as early as the 3rd century A.D.

The more "modern" elucidation of the electromagnetic force is attributed to several scientists throughout history, but one of the earliest modern scientists to really become associated with it is William Gilbert. An English physician and natural philosopher in the 16th century, Gilbert conducted extensive research on magnetism and electricity and was the first to use the term "electric force," "electric attraction," and "magnetic pole" to describe the phenomenon of attraction between electrified bodies.

In the 18th century, Charles-Augustin de Coulomb, a French physicist, formulated Coulomb's law, which describes the electrostatic interaction between electrically charged particles. He was also the first to recognize that the strength of the electromagnetic force between two charges is proportional to the product of their respective charges and inversely proportional to the square of their distance from one another.

And while popular myths in the U.S. mark Benjamin Franklin as the "discoverer" of electricity (or at least its association with lightning), this isn't actually the case. The connection between lightning and electricity had been discussed long before Franklin's kite experiment, but what Franklin was more interested in was how to protect wooden homes from catching fire from a lightning strike. His kite experiment using a metal key as a conductor was more to develop an early form of lightning rod to channel the electricity from lightning away from the wooden structures of the era.

Another major contributor to our understanding of the electromagnetic force was the British physicist Michael Faraday, who discovered electromagnetic induction, the key innovation that helps power electric motors and generators.

Many more scientists contributed to the incremental understanding of the electromagnetic force well into the present day, with Albert Einstein and Richard Feynman being two of the biggest contributors during the 20th century.

PiccoloNamek / Wikimedia Commons

Electricity refers to the flow of electric charge, usually through a conductor such as a wire. The movement of electric charge creates a magnetic field, and the interaction between electric charges and magnetic fields gives rise to the electromagnetic force.

The electromagnetic force is a fundamental force of nature that describes the interactions between electrically charged particles like electrons and protons, as well as the behavior of electric and magnetic fields.

In essence, electricity is a phenomenon that arises from the movement of electric charge, whereas the electromagnetic force is a fundamental force that describes the interactions between electrically charged particles. While the two are intimately related, electricity and the electromagnetic force are two different things and shouldn't be considered synonymous.

D-Kuru / Wikimedia Commons

Much like electricity and electromagnetic force are separate but related concepts, electromagnetic radiation is deeply tied to the electromagnetic force but is not the same thing.

The electromagnetic force arises from the interaction between electrically charged particles. It can be either attractive or repulsive, and it is responsible for a wide range of phenomena, from the behavior of atoms and molecules to the properties of materials and the functioning of electronic devices.

On the other hand, electromagnetic radiation refers to the waves or particles of energy that are produced by the motion of electrically charged particles. Examples of electromagnetic radiation include radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. Electromagnetic radiation is characterized by its wavelength or frequency and its amplitude, and it can have a wide range of effects on matter, including heating, ionization, and chemical reactions.

So, electromagnetic radiation is better thought of as a consequence of the electromagnetic force in action, specifically the waves or particles of energy produced by the motion of the charged particles under the influence of the electromagnetic force.

The electromagnetic force is transmitted by particles called photons.

Photons are elementary particles that have no electric charge, no rest mass, and travel at the speed of light in a vacuum.

Photons are produced when an electrically charged particle, such as an electron, undergoes a transition from a higher energy level to a lower energy level. This process is called photon emission. Conversely, photons can be absorbed by charged particles, causing them to undergo a transition to a higher energy level.

They are often referred to as "particles of light" because they are responsible for carrying electromagnetic radiation, including visible light, radio waves, and X-rays. More than anything, it is the one fundamental force carrier that we can plainly 'see' since photons are the reason why we can even see in the first place.

Photons also play a crucial role in a wide range of phenomena, including photosynthesis and the generation of electrical power in solar cells. Their unique properties have also enabled scientists to develop a deeper understanding of the nature of light and the behavior of matter at the quantum level.

The strength of the electromagnetic force gives it an outsized impact in the everyday world, as it absolutely dominates gravity and the weak and strong nuclear forces.

This also has a lot to do with a key characteristic of the electromagnetic force, which is that its influence can traverse very long distances, unlike the strong and weak nuclear forces, which are only able to wield influence at subatomic scales.

This doesn't mean that the electromagnetic force isn't strong at the quantum scale, however.

The strength of the electromagnetic force is determined by the coupling constant, which is a measure of the strength of the interaction between charged particles. The value of the coupling constant is approximately 1/137, making the electromagnetic force much stronger than the weak and strong nuclear forces at everyday energies.

However, things get much fuzzier at very high energies, such as those found in particle accelerators and in the early universe. In these circumstances, the strength of the electromagnetic force can be comparable to the weak and strong nuclear forces, and at especially high energies, the electromagnetic force and weak nuclear forces become so closely intertwined as to become a single electroweak force.

And at these energies, the electromagnetic force can interact with particles in ways that are not observed at lower energies, making high-energy experiments especially useful for probing the limits and capabilities of the electromagnetic force.

NASA / WMAP Science Team

The electromagnetic force is believed to have originated during the very early stages of the universe, just after the Big Bang. At that time, the universe was extremely hot and dense, and its particles were in a state of high energy and intense activity.

Cosmologists believe that the electromagnetic force emerged from a unified force known as the electroweak force. This force was a combination of the electromagnetic force and the weak nuclear force, which is responsible for certain types of radioactive decay.

As the universe cooled and expanded, the electroweak force underwent a process known as symmetry breaking, causing it to split into two distinct forces: the electromagnetic force and the weak nuclear force.

This process occurred about 10-10 seconds after the Big Bang, when the temperature of the universe fell below a critical threshold known as the electroweak scale, which is estimated to be around 100 billion electron volts (GeV). Temperature-wise, this would be around 1015 Kelvin.

theasis / iStock

The electromagnetic force doesn't absolutely permeate our lives technologically, but it's getting pretty darn close.

Right out of the gate, if you live in an electrified region of the world, the electromagnetic force will play a key role in just about everything in your life, from traffic lights to the phone in your pocket and the radio signal you communicate through, and the television you watch.

Everything boils down to electricity generation, and this is fundamentally driven by our harnessing the electromagnetic force to drive industry. Electricity generation is the process by which a changing magnetic field induces an electric current in a conductor, such as a coil of wire, which can then be transmitted via wire or even wirelessly to where it's needed.

The behavior of electrons, which are negatively charged particles, is governed by the electromagnetic force. This is the foundation of electronics, including computers, televisions, and smartphones. The electromagnetic force is also responsible for the interactions between electrons in circuits and the transmission of signals through wires and wireless networks.

Electric motors and generators rely on the electromagnetic force as well. When an electric current flows through a wire, it creates a magnetic field that interacts with other magnetic fields in a way that can produce motion in electric motors, which can be used to transport heavy cargo or people or harnessed to some other tool to produce work.

In medicine, magnetic resonance imaging (MRI) uses the electromagnetic force to create detailed images of the human body. It works by using a very strong magnetic field and radio waves to manipulate the spin of protons in the body's tissues, which are then detected by sensors to create an image.

Finally, the electromagnetic force is essential for our entire modern communication infrastructure, including radio, mobile phones, and the internet. These technologies rely on the transmission of electromagnetic waves through the air to send and receive information.

All matter in the universe, including the atoms that make up everything we see and experience, rely on the electromagnetic force to hold their structure and properties. Without the electromagnetic force, matter would no longer be able to hold together, and the universe as we know it would cease to exist.

Chemical bonds between atoms, such as those in water, proteins, and DNA, are created and held together by the electromagnetic force. Without this force, these bonds would break down and molecules would fall apart into their constituent atoms. The structure and stability of all solids, liquids, and gases would be lost, and the world as we know it would become an amorphous and chaotic mix of particles.

In addition to its crucial role in the structure of matter, the electromagnetic force also plays a key role in many natural phenomena. For example, the electromagnetic force is responsible for the behavior of light and other forms of electromagnetic radiation, and it is essential to the functioning of electronics and other technological devices.

Without the electromagnetic force, the universe would be a vastly different and unrecognizable place, and life as we know it would be impossible.

While the electromagnetic force is well-understood and plays a fundamental role in the behavior of matter, there are still some open questions in physics related to its properties and interactions.

One of the biggest open questions in physics is how to reconcile the electromagnetic force with gravity, which is another fundamental force that governs the behavior of matter on a larger scale. While the other two fundamental forces, the strong and weak nuclear forces, have been shown to merge into a single electroweak force at the high energies present immediately after the Big Bang, attempts to unify this with gravity have so far been unsuccessful.

Another unresolved issue is that of dark matter. Scientists believe there is far more matter in the universe than can be accounted for by the observed visible matter. This "dark matter" is thought to interact weakly with normal matter and is often considered a prime candidate for a new physics beyond the Standard Model. It isn't clear if the electromagnetic force would interact with dark matter in any way, as no interaction has been observed as of yet.

More practically, at very high energies like those found in particle accelerators, the electromagnetic force can exhibit unexpected behaviors that are not well understood. Another unresolved problem is the theory of quantum electrodynamics (QED), which describes the behavior of the electromagnetic force with remarkable accuracy but still has some subtle effects that are difficult to fully understand and calculate.

One such effect is the Lamb shift, which refers to a small deviation in the energy levels of hydrogen atoms caused by the interaction between the electron and the electromagnetic field.

Overall, while the electromagnetic force is among the most well-understood of the four fundamental forces, it still holds the promise of more secrets to uncover and explore. And given the prominence of the electromagnetic force in powering so much of our modern technology, there's every reason to hope that further discoveries will take us even further than we thought possible.