Electromagnetic induction creates electricity from a changing magnetic field

Watch a timeline of the history of electricity, from observations of static electricity in antiquity to the War of the Currents—a rivalry to establish the ideal system for electric grids.

Metal detectors identify induced magnetic fields in conductive objects

A changing magnetic field in a transmitter coil causes an electric current to be produced in materials that conduct electricity. This current generates its own magnetic field, which can be detected by a receiver coil and transmitted to a control box, which identifies the presence and depth of an object.

Visualize how alternating currents—electricity that periodically changes direction—are generated by rotating magnetic fields, as occurs in turbine-generator systems.

Transformers change the current and voltage across a set of wires by wrapping them around a magnetic core and using the magnetic field of one wire to induce a current in the other.

A dispute about the origin of twitching frog legs led to the invention of the first battery

Experiments by Luigi Galvani on exposed frog leg nerves showed activity when they were hung from iron railings and brass hooks, suggesting the existence of "animal electricity" that discharged when connected to metals. Alessandro Volta's voltaic pile, which stacked metals with an inorganic electrolyte, showed that electricity originates from chemical reactions.

In 1880, Jacques and Pierre Curie discovered that electricity could be produced by striking certain materials—the piezoelectric effect—a phenomenon that is seen in barbecue lighters.

If two strands of conducting materials are connected at two junctions, electricity can be generated if one junction is heated while the other is cooled—a phenomenon known as the Seebeck effect.

The dynamo theory explains how planets generate their own magnetic fields

According to the theory, a large magnetic field generator, or dynamo, is created when liquid metal flows through the planet's outer core, producing electric currents that generate a magnetic field. Magnetization patterns in rocks on the surface of planets can serve as evidence for the presence of this internal structure at some point in the celestial object's past.

Named after Nikola Tesla, who pioneered alternating current power systems, the Tesla coil was the first device to wirelessly transmit electricity.

Despite promoting alternative current, Nikola Tesla did not invent it

The technology was developed by Hippolyte Pixii in 1832, almost 25 years before Tesla was born. Other myths about Tesla include that he invented the transformer, radio, and the induction coil, which was invented by Nicholas Callan in 1836.

Wireless charging uses a magnetic field to move charged particles in a battery

Based on the concept of electromagnetic induction, when a compatible device is placed on a charging pad with correct alignment, the alternating current flowing through the pad creates a changing magnetic field. This magnetic field induces a current in the device, recharging the battery without a connecting wire.

Fluxgate magnetometers detect magnetic fields using electromagnets

Instead of a compass needle's movement indicating a magnetic field, an alternating current produces an oscillating magnetic field in a metal bar. An external magnetic field creates an imbalance in the oscillations, which can be measured quantitatively.

The movement of molten metal around Earth's inner core creates the planet's magnetic field, whose north and south poles do not align with the planet's geographic poles.

Ray Bradbury said he was inspired to pursue writing after meeting a magician named Mr. Electrico, but scholars have never been able to confirm the story.

Benjamin Franklin described a series of static electricity storage jars as 'batteries'

Discovered over 50 years before the first electrochemical cell was invented, Leyden jars stored electric charge between the metals inside and outside a liquid-filled container. Franklin was the first to use the term "battery" in an electrical sense, though his multiple-jar device—lacking chemical reactions—was actually a series of capacitors.

The speed of electricity may refer to the movement of electrons, which is on the order of a fraction of a millimeter per second, or energy, which is near the speed of light.

Before the invention of transistors, vacuum tubes made radio possible

Discovered by Thomas Edison, vacuum tubes allow electrical currents to travel through empty space. Later modified into a diode—keeping current flowing in only one direction—vacuum tubes allowed electronics to turn alternating current into direct current.

Electricity is produced when the ends of a battery are connected by a conducting wire, triggering chemical reactions that release the energy stored in chemical bonds.

Certain objects are magnetic because their electrons' magnetic moment—an intrinsic quantum property—align within the object in specific patterns.

Tesla's alternating current power's most of the world's electric grids

In 1879, Thomas Edison’s light bulb relied on direct current, but such currents can't efficiently transmit power over long distances. Nikola Tesla introduced alternating current, which feature far fewer energy loses. Despite Edison’s attempts to discredit AC, Tesla proved its efficiency by lighting the 1893 Chicago World’s Fair.

Fluorescent bulbs can be illuminated by overhead power lines without making contact

The electromagnetic fields produced by the alternating current in transmission lines can induce the motion of charges in nearby objects. This motion yields electric currents that can light up bulbs but are too small to harm humans.

Nikola Tesla embraced showmanship when promoting ideas ahead of their time

He once electrified himself during a live demonstration to illustrate the safety and power of alternating current, and his presentations often featured arcing coils, glowing lights, and bold claims about a future of wireless power.

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

Faraday cages protect enclosed objects by redirecting electrical currents

Constructed from conductive materials, the cage allows electrons to distribute themselves evenly throughout its surface and travel to ground, keeping the interior neutrally charged and preventing any internal electricity. The same principle blocks electromagnetic waves by redirecting the electric field component, preventing telecommunication signals from entering the apparatus.

Electrogenic animals generate their own electricity within an electric organ by changing the pattern of electrical charges in disc-shaped cells called electrocytes.

Electricity can flow indefinitely along a ring of superconducting material, which provides zero resistance to the movement of charges due to quantum effects.

Cathode rays are beams of electrons that emit light when hitting a fluorescent screen

When these beams are emitted into an evacuated tube containing charged plates or a nearby magnet, deflections are observed due to the electron charge. In 1897, J.J. Thomson's calculations of this deflection led to his discovery of the subatomic particle.

Pierre Curie's knowledge of electromagnetism helped decipher radioactivity

Alongside his brother, he studied electric fields in crystals and the magnetic properties of substances, which required the construction of delicate electrometers. He would use this apparatus with Marie Curie to measure radioactive emissions and the presence of undiscovered radioactive elements.

Temperatures colder than Pluto can allow electricity to flow resistance-free

Since its discovery in 1911, applications of superconductivity have made MRI machines and maglev trains possible due to quantum effects at extreme temperatures. These effects are modeled as electrons cooperating in pairs and flowing more efficiently.

Thomas Edison publicly executed animals with AC to convince the public of its dangers

J.P. Morgan first backed Thomas Edison's direct current system, seeing electricity's potential to usurp John D. Rockefeller's kerosene empire. Despite the investments and smear campaign against alternating current, alternating current ultimately won public support after lighting the 1893 World's Fair, after which Morgan would fund Tesla's wireless transmission tower.

Simulate the buildup and discharge of static electricity through friction by dragging the arm and leg of 'John Travoltage' along surfaces.

Magnetic material in rocks provides evidence of flips in Earth's magnetic field

Volcanic rocks can lock in the direction of Earth's magnetic field as they cool, making them natural recorders of magnetism. Dating rocks and seeing the changing orientation of their magnetic field helps construct a timeline of Earth's magnetic field history.

Tesla's first successful AC prototype used a metal shoe polish tin for a rotor

After leaving his position working with Thomas Edison, Tesla partnered with George Westinghouse to promote alternating current systems as a more viable, scalable solution to electricity transmission.

Alternating current was used to commit the first execution by electric chair

Dubbed the "executioner's current," the device was designed in Thomas Edison's lab by Harold Brown—an opponent of George Westinghouse and Nikola Tesla. The effort aimed at discrediting AC technology and gain favor for Thomas Edison's direct current as part of "The Current War."

Earth is the only terrestrial planet with a magnetic field

Its magnetosphere emerges from a complex interior process of electrical conduction, heat, and motion known as the geodynamo. The magnetic field shields the Earth from unsafe cosmic radiation, providing one of the many conditions required for life.

In the photovoltaic effect, light generates electricity by creating a charge imbalance after knocking electrons out of atoms in the semiconducting materials of solar cells.

The strongest recorded geomagnetic storm in history created auroras near the equator

On Sept. 1, 1859, the Carrington Event—named after the astronomer who observed the preceding solar flare—saw a massive coronal mass ejection strike Earth, disrupting telegraph systems, sparking electrical fires, and reportedly illuminating the night sky enough to allow newspapers to be read at night.

Radioactivity was accidentally discovered when uranium left marks on photographic plates

In 1896, Henri Becquerel had been exploring phosphorescence—the emission of light of one color after an object is exposed to another color. He expected these emissions to come from objects exposed to sunlight, but he observed emissions after an overcast day.

In 1898, Nikola Tesla wowed a crowd by controlling a boat with no visible connection

Some onlookers thought it was a trick, such a a monkey being inside the boat, rather than mind control or some other metaphysical phenomenon. In reality, Tesla was pioneering radio waves, proving wireless control was possible.

Earth's magnetic field can trap high-energy charged particles produced by the sun and distant cosmic events in doughnut-shaped rings called Van Allen belts.

A collective effort from multiple scientists and inventors led to the light bulb

While Thomas Edison's thin carbon filament design made light bulbs commercially viable, prior contributions, such as Joseph Swan's development of the first successful incandescent filament electric lamp, made its eventual invention possible.

The electric microphone led to a country music boom

The electric microphone provided enhanced audio and greater portability, saving the fledgling record industry and making recording outside of New York and Camden, New Jersey, possible. This proved critical for capturing early country and rock ‘n’ roll.

Measurements of an electron’s magnetic moment help test the Standard Model

A particle’s magnetic moment quantifies how it responds to the presence of an external magnetic field. An electron’s value can be measured down to 14 decimal places, with certainties in the first 12 allowing it to be used to assess the accuracy of predictive models.

Hacking the body for a future that didn't happen

Journalist Adi Robertson experimented with one of the most accessible biohacks: magnets. Having a tiny magnet in their right ring finger meant they could sense magnetic fields, attract small metal objects, and more. But magnets weaken over time, eroding this new sense. Such implants do more than offer a new way of interacting with the world, they also pose new complications, such as the inability to get an MRI.

Niagara Falls helped decide the battle between AC and DC power

In the 1890s, Niagara Falls became the proving ground for alternating current (AC) when Tesla and Westinghouse built the first large-scale AC hydroelectric plant—defeating Edison’s push for direct current (DC) in the US electrical system.

Lightning rods provide a conductive pathway to safely steer massive electric currents

The device is positioned higher above the ground to "catch" one of the many branching filaments of electrons from clouds before they make contact with other surface structures, which have been induced to have a positive charge by overhead storm clouds. The current is then sent to a conductive grid buried underground.

The engineering underlying the electric grid and why it needs to be modernized

The system includes generators for producing electricity and millions of miles of transmission and distribution lines to transport the energy. The substantial increase in the number of electronic devices and electrical demand since the construction of much of the grid in the mid-1900s has strained infrastructure, requiring continuous upgrades and massive investments in new construction.

Nikola Tesla was born in modern-day Croatia and moved to the US in 1884

His interest in electricity came from his mother, who invented small household appliances during Tesla's upbringing. Upon arriving in America, he began working for and improving upon the electrical inventions made in Thomas Edison's lab.

Planeterrellas create artificial auroras that mimic the atmospheric displays of light by setting up an electric field between two metal balls in a jar filled with a small amount of air.

The magnetic constant sets the strength of magnetic fields

The permeability of free space, or μ₀, contributes to the speed of light in the universe—a fundamental constant. It also helps quantify how the movement of electric charges generates a magnetic field and vice versa.