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.

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

Electromagnetic induction creates electricity from a changing magnetic field

The phenomenon was discovered in 1831 by Michael Faraday when an electric current was induced in a wire wrapped around an iron ring after a second wrapped wire not connected to the first was connected or disconnected from a battery.

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.

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.

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

While charges consistently move in the same direction in a direct current, the flow of charges changes multiple times per second in an alternating current.

Visualize how transformer architecture generates a large language model's outputs by running words and subwords assigned to specific numbers through multiple rounds of mathematical processing.

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.

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."

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.

Explore an interactive graphic of a wind turbine's components

Wind turbines contain a gearbox that increases the rotation of the blades by a factor of 100 from low to high-speed shafts. The latter moves magnets that change the magnetic field within a generator, creating electricity.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Transistors are the foundational components of integrated circuits and microchips and manage the processing of electronic signals by controlling the flow of electricity.

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.

Thunder occurs when fast-flowing electricity heats and pressurizes air, causing it to expand and produce a shockwave at each point along the bolt at multiple frequencies.

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.

Learn why electrical substations are needed to provide safe electricity with minimal energy loss

These typically fenced-off facilities with steel boxes or cylinders topped with cone-like caps house circuit breakers, fuses, and switches that can isolate sections of the grid to prevent electrical failures from spreading. Substations use transformers to modify electrical voltage and are customized to the generation, transmission, and distribution networks they interconnect.

George Westinghouse purchased Tesla's AC technology patents for $60,000

The seven patents in alternating current motors and power transmission formed the basis for a system of technologies including generators, transformers, and lighting. Nikola Tesla spent half the funds on a new laboratory to develop new inventions.

How its uneven rotation produces the sun's 11-year cycle and flips its magnetic poles

While charged material rises and falls in the sun's convection zone, which induces magnetic fields, different latitudes rotate at different rates, making these fields increasingly turbulent. This builds to a critical point—the solar maximum—where magnetic field-driven events, such as solar flares, become more common before the field collapses and flips, restarting the cycle.

In osmotic power systems, the natural movement of water from regions of low to high salt concentration is used to generate electricity from pressurized water.

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 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.

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

Before transistors, which regulate the flow of electricity, vacuum tubes—glass tubes containing no gas that resemble light bulbs—served as the electronic switches in computers.

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.

Explore how excitatory cells, such as neurons and muscle cells, transmit information in the body via electrochemical signals, which can travel up to 120 meters (390 feet) per second.

While gas-powered engines typically have 2,000 moving parts, electric vehicles have about 20.

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 total length of superconducting wire at the Large Hadron Collider spans about 250,000 kilometers (155,000 miles)—enough to wrap around the equator 6.2 times.

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

There is a limit to how small transistors can become because they rely on being able to allow or block the flow of electrons, but quantum effects allow electrons to leak through these barriers, generating heat, current loss, and potential data errors.

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.

Electricity can be lethal because it can disrupt the nervous system, which controls critical bodily functions that rely on electrical signals between cells, such as breathing and heart rate.

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

Simulate the effects of changing supply and demand on the electric grid

In this application, users can modify the demand of fictional cities and the supply of various generators, including a nuclear power plant and a wind farm, which can be disconnected from the grid. Notice that current may flow into or out of external systems to compensate for available generation. See what it takes to cause a blackout in different cities or shut down the entire grid.

Neurons send signals through electrical impulses and chemical messengers

By converting electrical signals into chemical messages at synapses, neurons allow information to travel throughout the nervous system. With repeated use, synapses grow stronger, enhancing the associations between neurons.

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.

How brain cells carry information

At any moment, there is an electrical storm coursing through your body. Discover how chemical reactions create an electric current that drives our responses to everything from hot pans to a mother’s caress.

The history of the North American power grid, which is composed of five major grids

Thomas Edison's Pearl Street Station was the first US commercial power plant, burning coal to power lamps for some Manhattan residents. Over time, local power plants would be bought out by larger ones, forming interconnected systems spanning multiple states. Today, the Eastern Interconnection and Western Interconnection are the largest of these systems.

An overview of radioactivity, which can spontaneously change one element into another

Unstable atomic nuclei can transmute into a new element—an atom with a different number of protons—by emitting an alpha particle (two protons and two neutrons) or a beta particle (an electron). The electron can emerge from the nucleus when a neutron, which has no charge, suddenly transforms into a proton and an electron, thereby maintaining zero charge before and after the transformation, but altering the original element.

More batteries in the power grid would create an on-demand energy reservoir

Most power grids are inefficient because they require enough generation capacity at all times to avoid blackouts. This means at any given time, as much as 50% of generating capacity at power plants can go unused. Batteries would reduce this inefficiency and allow for real-time adjustments.

Lightning is the sudden flow of electricity in the atmosphere as two oppositely charged regions seek to become balanced via the movement of electrons.