The Development of Electromagnetism

Just two months after Ørsted's publication, a French mathematician and scientist, André-Marie Ampère, learned of his discovery. Ampère expanded on Ørsted's experiments by developing methods to quantify the magnetic forces generated by electric currents.

He theorized that if two magnets influence each other and an electric current can affect a magnet, then two electric currents should similarly interact. By arranging two wires in parallel and varying the current flowing through each, Ampère measured the forces exerted between them.

His findings revealed that when both wires carried current in the same direction, they attracted one another, while opposing currents caused repulsion. He established that the force's strength is directly proportional to the product of the two currents.

Moreover, he discovered that the force's intensity diminishes with distance; specifically, it is inversely proportional to the distance between the wires. For instance, doubling the distance between the wires resulted in halving the force.

Ampère further generalized this behavior into a formula that predicts the forces generated by any shape of wire carrying an electric current, now known as the Ampère force law.

The Revolutionary Solenoid

Ampère advanced the concept even further by recognizing that his formula suggested a way to create stronger magnetic forces through coiling wire into loops. He validated this by constructing a solenoid, a coil that could generate magnetic forces significantly more powerful than those of a straight wire.

The invention of the solenoid marked a significant technological advancement. In the ensuing decades, scientists and inventors utilized solenoids for various groundbreaking applications:

• In the 1830s, solenoids became integral components of the first practical electric motors, which transformed industry and transportation.
• By 1840, Samuel Morse had perfected the electric telegraph, employing a solenoid to pull a strip of iron against a spring, creating sounds interpretable as letters. This innovation linked cities across the U.S. and Europe, establishing a global telegraph network by the late 19th century.
• Powerful solenoids capable of carrying substantial electric currents were developed for studying material magnetism, leading to discoveries about previously deemed non-magnetic substances.
• Connecting solenoids to a paper cone near a permanent magnet allowed electricity to produce audible vibrations, forming the basis for speakers in radios and televisions.
• Solenoids also became fundamental components in relays, actuators, transformers, and electromagnets.

The Reverse Effect

In 1831, English scientist Michael Faraday was investigating a pair of solenoids positioned close to each other. He discovered that initiating or halting current flow in one solenoid induced a brief current in the other. However, once the first solenoid's current stabilized, there was no further effect on the second.

Faraday posited that a shifting magnetic field could generate an electric current in a nearby conductor, confirming this hypothesis by moving a magnet in and out of a solenoid.

The Invention of the Electric Generator

Faraday utilized his findings to create the first practical electric generator, which operates as a motor in reverse, converting mechanical energy into electrical energy.

Prior to generators, most electricity was produced by chemical batteries, which had limited power and lifespan, and posed safety risks due to their hazardous materials.

The advent of generators facilitated the large-scale production of consistent electrical power. When paired with steam engines or water turbines, they enabled the electrification of entire cities and powered trolleys and trains without the noise and pollution of coal engines. This innovation opened doors to new chemical processes, including the mass production of affordable aluminum, fundamentally transforming our electrical landscape.

The Emergence of Electromagnetic Radiation

As the 19th century progressed, scientists continued to deepen their understanding of electricity and magnetism. Scottish physicist James Clerk Maxwell became intrigued by how electric currents could exert magnetic forces at a distance, and how a moving magnetic field could induce an electric current.

Building on Ampère and Faraday's work, Maxwell published a comprehensive set of equations in 1862 that elucidated the behaviors of electric and magnetic forces, viewing them as two facets of a unified electromagnetic field.

By 1873, Maxwell recognized that his equations suggested the existence of a novel form of energy: electromagnetic waves traveling through empty space. His calculations indicated these waves should propagate at the same speed as visible light.

Maxwell theorized that light was, in fact, a form of electromagnetic radiation, marking a monumental achievement in understanding light through mathematical theory.

The Discovery of Electromagnetic Waves

In 1887, German physicist Heinrich Hertz confirmed Maxwell's prediction by successfully generating electromagnetic waves. He created a setup that allowed large electric sparks to leap between two metal spheres, and observed tiny sparks jumping across a gap in a distant wire loop, marking the first radio transmission.

Hertz's experiment validated Maxwell's theory of electromagnetic radiation, and he took pride in his accomplishment. However, when questioned about the practical applications of his work, he humbly replied, “probably nothing.”

The Golden Era of Radio

In retrospect, Hertz's apparent lack of foresight is amusing. Within a few decades, innovators like Guglielmo Marconi harnessed Maxwell's theories and improved upon Hertz's devices to develop the first viable radio systems.

By the 1910s, ships were communicating via radiotelegraphs, and by the 1920s, vacuum tube oscillators replaced earlier spark-gap transmitters, leading to commercial radio stations broadcasting music and voice.

Radio technology evolved rapidly, filling the airwaves with an array of sounds and images. In July 1969, viewers worldwide witnessed astronauts walking on the moon live on television. Today, we are interconnected through satellites, computers, microwave towers, and extensive networks of signals.

The Joy of Discovery

Reflecting on the extraordinary advancements since Ørsted noticed the compass needle's subtle movement, it is clear he could not have foreseen the profound impact of his observation.

He received numerous accolades and honors from grateful colleagues, which surely brought him satisfaction.

Nevertheless, it is likely he understood—and we can too—that if he had not discovered the interplay between electricity and magnetism, someone else would have eventually made the same connection. When the time is right for a discovery, it is bound to occur somewhere, by someone. We often celebrate the individual who reaches a milestone first, as if all depended on them.

This does not diminish Ørsted's contribution; he not only observed something novel but also diligently explored it and shared his findings. Others might have overlooked that shifting needle after a mere shrug.

I like to think Ørsted’s true reward was not merely the accolades he received, but a profound, personal thrill. He experienced the extraordinary gift of curiosity and the joy of discovery—a quality we can all nurture. Whether or not we are the first to notice a phenomenon is irrelevant; the essence lies in fostering curiosity and marveling at the wonders of nature, a joy that belongs to all of humanity.