How a kite in a lightning storm led to the science behind Wi-Fi and MRI machines

In that moment, Franklin showed that lightning and the crackle from a rubbed amber rod were manifestations of the same force: electricity.

For decades, electricity and magnetism were studied as if they were separate curiosities. But in 1820, Hans Christian Ørsted showed an electric current could deflect a compass needle. Electricity, it turned out, could create magnetism.

A year later, Michael Faraday built on that insight. In 1821, he demonstrated the first electric motor — a rotating wire spinning around a magnet. When an onlooker reportedly sniffed, “But of what use is it?” Faraday calmly replied, “Of what use is a newborn child?”

His answer captured the spirit of discovery: utility often comes long after understanding.

The Force That Shapes Our Lives

Electromagnetism is the fundamental force that unites electricity and magnetism. It is one of the four fundamental forces of nature – alongside gravity, the strong nuclear force, and the weak nuclear force. Unlike gravity, which only attracts, the electromagnetic force both attracts and repels. It governs the behavior of charged particles, binding electrons to nuclei to form atoms and, in turn, molecules. Without it, chemistry would not exist, and neither would life.

It also operates on scales we encounter every day. The repulsion between electrons in your chair and in your body keeps you from sinking through it. The attraction of charges makes magnets stick to fridges and lets birds navigate using Earth’s magnetic field. In short, electromagnetism runs through nearly every aspect of daily life.

How electromagnetism is a practical force

The electromagnetic force is not just theoretical — it is deeply practical. It powers MRI machines in hospitals, generates the current that lights our homes, and makes the touchscreens on our phones respond to our fingers. From communication satellites to microwave ovens, this single force underpins much of modern technology.

Some of its most familiar uses include:

🧲Transport: Electric motors drive trains, cars, and even bicycles.

🧲Medicine: X-rays, MRI scans, and radiotherapy all rely on electromagnetic interactions.

🧲Communication: Radio, television, Wi-Fi, and mobile networks send signals through electromagnetic waves.

🧲Energy: Generators, transformers, and the entire power grid operate because moving charges create magnetic fields and vice versa.

🧲Navigation: Compasses align with Earth’s magnetic field, while GPS satellites use atomic clocks based on electromagnetic transitions.

Franklin’s  brush with death gave rise not only to lightning rods, which protect buildings to this day, but to much of modern technology that runs our daily life.

From Maxwell to Modern Physics to QED

The unification of electricity and magnetism came in the 19th century through the work of James Clerk Maxwell. His four elegant equations described how electric and magnetic fields interact, predicting that light itself is an electromagnetic wave.

Albert Einstein later built upon this. In his theory of special relativity, he showed that the speed of light is a universal constant, inseparable from the nature of space and time. This was revolutionary: it meant that electromagnetism was not merely one force among others, but a cornerstone in understanding the structure of reality itself.

By the mid-20th century, physicists went even deeper. They developed quantum electrodynamics (QED), a theory that explains how light and matter interact at the tiniest scales. In simple terms, it says that particles like electrons “talk” to one another by tossing photons back and forth, like exchanging invisible messengers. Even what we think of as empty space isn’t truly empty — it constantly flickers with brief, ghostlike particles that appear and vanish in an instant.

What makes QED remarkable is its precision. The theory can predict the magnetic properties of the electron to more than ten decimal places, agreeing with experiments almost digit for digit. Richard Feynman, one of its architects, once called QED “the jewel of physics” because of this extraordinary accuracy. It remains one of the best-tested scientific theories ever created — and the foundation of modern particle physics.

Why electromagnetism matters

The electromagnetic force is the glue of everyday reality. It explains the shimmer of light, the hum of power lines, the spin of hard drives, and the guidance systems of migrating birds. It is the most versatile of the fundamental forces, linking the microscopic world of particles with the macroscopic world of human experience.

From Franklin’s kite to Faraday’s motor to Einstein’s equations and today’s quantum electrodynamics, the story of electromagnetism is one of curiosity, courage, and creativity. It shows us how abstract ideas can become the foundation of modern life — and how the sparks of imagination can one day light up the world.

Shravan Hanasoge is an astrophysicist at the Tata Institute of Fundamental Research.