Electromagnetic induction creates electricity from a changing magnetic field

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.

How electricity is generated by heating water into steam, which rotates magnets

Electrical current—the flow of electrons in a wire—can be produced when exposing a wire to a changing magnetic field. By rotating the magnets, as occurs in a turbine-generator system, the field changes become cyclical. This produces alternating current—flow that moves forward and backward—converting mechanical energy into electrical energy.

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.

Movement of molten metal around its solid inner core creates Earth's magnetic field

According to the geodynamo process, the rotation of the planet and the looping, convective flow of electrically conductive iron and nickel produce dynamic electric currents, which generate a self-sustaining magnetic field. This is unlike natural, stationary magnets, which possess a static field created when the metal cooled and its atoms aligned with Earth's magnetic field.

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.

The Tesla coil was the first system to wireless transmit electricity

Developed in 1891, the system effectively consists of two open electric circuits with a gap of air between them. When a high enough voltage is built up, air becomes a conductor and sparks of electricity are generated.

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.

Magnetism comes from quantum properties of electrons aligning in specific structures

Permanent magnets exist because electrons have an intrinsic magnetic moment, which can align in certain atoms. When many such atoms line up their magnetic fields within regions called domains, the result is a visible, macroscopic magnetic effect.

Discoveries in electromagnetism became the catalyst for overturning Isaac Newton

To maintain the consistency of experimental results involving electricity, magnetism, and light, time and space had to cease being absolute and could change in value to keep the speed of light constant. This cosmic speed limit forced Einstein to revise the existing model of gravity.

How electrical transformers use coils of conductive wire to change voltage levels

Two sets of wires are wrapped around a magnetic core, each a different number of times. As alternating current flows through one wire, it generates a changing magnetic field that induces an alternating current in the second wire. If the second wire has fewer coils, the voltage steps down—decreases. If the second wire has more coils, the voltage steps up.

The speed of electricity may refer to the movement of electrons or energy

In the 18th century, various experiments, including one in which monks holding an iron wire were shocked, suggested that electricity traveled at infinite speed. Advancements in technology, recognizing that electric currents were moving electrons, and the development of the theory of electromagnetism showed that electric signals can travel at near light speed, despite electrons moving much slower.

Pierre Curie found electricity could be generated by compressing certain crystals

Jacques and Pierre Curie discovered the piezoelectric effect in 1880. Pierre incorporated it into an apparatus used by Marie Curie to discover polonium and radium. This phenomenon is seen in barbecue lighter ignition mechanisms, where quartz is struck to create a spark that ignites fuel.

Light energy can be transformed into electricity in solar cells via the photovoltaic effect

When light strikes semiconducting material, it can knock electrons out of atoms, creating a charge imbalance within the material. A wire connecting the oppositely charged regions can allow electrons to flow back, balancing the charges and producing an electric current that can be harnessed to power devices.

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.

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.

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.

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.

Electromagnetic repulsion prevents objects from making contact with one another

The feeling of touching something is a sensation caused by the electromagnetic force between the electrons on the surface of objects. Since this force grows to infinity with proximity, no two surfaces can ever achieve matter-to-matter contact.

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."

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.

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.

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.

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.

The first nuclear reactor was built three years after nuclear fission was discovered

After learning that large atomic nuclei release energy upon being split apart, scientists quickly researched how to control the reaction to make electricity. Fusion—combining small atomic nuclei—generates massive energy in stars and hydrogen bombs.

Dirty lightning is a thunderstorm created from friction between rising and falling flows of ash and smoke during volcanic eruptions.

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.

Ménière's disease was first identified in 1861

This condition is named after the French clinician Prosper Ménière, who first identified it as being linked to the inner ear, noting it was a disorder of the semicircular canals. It tends to occur in people who are 40 years old or older.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

Learn more about the history of fireworks, which dates back to an accidental invention during an alchemist's quest for information about immortality.

Discover the catastrophic consequences of a failure of the US electrical grid—something that is more likely than many Americans think.

The concept of phantom limbs, the perception that amputated limbs are still present, dates back to a French military surgeon in the 16th century.

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

The first horror movie is believed to be George Méliès' 1986 short 'The Haunted Castle,' which pioneered the use of special effects

Sony set the standard for cylinder-shaped batteries when it repurposed manufacturing equipment used to make rolls of magnetic recording tape.

Clever Hans was a 1900s horse that was believed to be able to solve math equations, tell time, and read and comprehend German, until a psychology student discovered how he got his answers.

Long before Major League Baseball began allowing instant replay for balls and strikes, an umpire reluctantly used the technology to determine whether a hit was a home run, a move that inadvertently ushered in a new era for the sport.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

Hurricanes, which rely on air consistently spinning in the same direction, cannot cross the equator because air curves in opposite directions north and south of it.

How Amazon operates a 'flywheel' business model, a self-reinforcing cycle that drives continuous growth

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

Abraham Lincoln was almost assassinated weeks before his inauguration as he traveled from Illinois to DC through Baltimore in 1861; it took two independent claims for Lincoln to be convinced the threat was real

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

Hookworm infection, though risky, may help fight certain autoimmune conditions by tamping down the immune system's inflammatory response.

One disco producer saw 'Star Wars' four times on its opening weekend and was so inspired that he recorded the album 'Star Wars and Other Intergalactic Funk,' which produced a chart-topping single.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

'Grand Canyon of the Yellowstone,' a work by American painter Thomas Moran, inspired Congress to establish Yellowstone National Park.