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

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.

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.

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.

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

Fast charging can lead to battery degradation if the device does not stay cool

Modern phones use software to monitor charging habits and can activate adaptive charging to delay charging rates and prevent overheating. When charging, devices should not be confined (e.g., stored in your pocket) or placed in direct sunlight, as this can trigger heat warnings and sudden shutdowns.

Contactless credit cards descend from a batteryless Cold War listening device

The same physics that let Soviet spies eavesdrop on the US ambassador in 1945 underlie contactless payment methods today. The device is a passive chip powered wirelessly by incoming radio waves.

The gradual loss of capacity in rechargeable batteries can be delayed by avoiding overnight charging, charging to 100%, fast charging, and exposing your device to excessive heat.

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.

Most advanced touch screens rely on electrical charge in your skin

Capacitive touch screens store electrical charges in an electrostatic grid of tiny wires. When we touch the screen a tiny electrical charge is transferred from the screen to the finger to complete a circuit (since skin has positive and negative charges). This connection creates a voltage drop on that point of the screen. Cloth, however, doesn't conduct electricity, which is why humans can't wear thick gloves and operate their smartphones.

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.

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.

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.

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

Boost your Wi-Fi with aluminum foil

A surprising hack using aluminum foil can potentially improve Wi-Fi signals, to many readers' surprise. Check out the science with this brief article. Wi-Fi signals spread like radio or light waves from a router's antenna, often leading to...

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.

Interacting sound waves can create regions where the pressure from each wave combines, allowing objects to levitate in place against gravity or be manipulated for touch-free construction.

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

Learn why magnets, like statically charged balloons, can deflect water

While the oxygen atom in water molecules strongly attracts hydrogen's electrons—producing an uneven charge distribution that pulls water toward balloons that have been rubbed against surfaces—the presence of a magnetic field alters the path of these electrons, which produce their own tiny magnetic fields. The interaction of these fields repels water away from magnets, making it diamagnetic.

Radio waves are used in broadcasting, weather radar, telecommunications, and GPS

Its ability to bend around obstacles and reflect off the ionosphere—an electrified layer of Earth's upper atmosphere—allows this type of light to travel long distances without damaging living things due to its low energy. MRI scanners, WiFi, and Bluetooth technologies are also applications of this form of light.

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.

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.

Microwave ovens heat food by agitating certain molecules with non-ionizing light

Molecules with resonant frequencies within the microwave range vibrate, producing heat between adjacent matter, just as hands warm when rubbed together. The mesh in front of an oven's door confines the microwaves to the container, while the rotating plate allows different parts of food to travel through regions of maximum vibration.

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.

Some materials can absorb low-energy light and emit high-energy radiation

Through anti-Stokes cooling, incoming energy is combined with vibrations in a material's crystal lattice to produce a net reduction in its temperature. Using this effect, lasers can be directed at microchip hot spots to help keep data centers cool.

Elon Musk's Neuralink's N1 chip can wirelessly read brain signals from over 2,000 electrodes

The device is a battery-powered brain implant that transmits data via Bluetooth. Neuralink's near-term objectives for the device focus on unlocking new treatments for paralysis, neurological disorders, and some psychiatric conditions.

Nikola Tesla's biggest dream was a worldwide network of wireless power transmission

He built the Wardenclyffe lab and a massive prototype transmission tower to develop trans-Atlantic transmission, but it was never operational. The concept was based on incorrect assumptions about Earth's conductivity, but it inspired subsequent efforts for wireless systems.

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.

Earth's magnetic field, which deflects charged particles, helps protect us from cosmic rays, but the sensitivity of these particles to magnetic fields also makes it difficult for astronomers to determine their sources.

Research shows that cosmic rays may trigger the cascade of displaced electrons needed to produce lightning, which is also enabled by pointed ice crystals that create strong electric fields.

Watch how metals are extracted from rechargeable devices during recycling

Recyclable batteries found in cars, phones, power tools, and other electronics contain lithium, cobalt, nickel, and other precious metals, whose reuse generates 70% fewer emissions than during their initial mining. Upon shredding these devices, a filter press squeezes the pieces through a proprietary fluid, which separates them for future reuse.

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.

Data centers can be kept cool by circulating fluid over plates atop high-temperature components or by submerging equipment in non-corrosive oil that does not conduct electricity.

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

You have never made physical contact with anything in your life because electrons in the outer layer of atoms on the surface of objects repel one another.

In 2026, researchers successfully transported antimatter in a truck using a portable trap that employed electromagnetic fields to hold 92 antiprotons.

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.

Water vapor is used to manage heat in high-end smartphones

While smartphones have traditionally been cooled using a highly conductive plate that dissipates heat from the chip, vapor chambers offer a higher heat-removal capacity. This technology has been utilized in laptops for decades to absorb heat by cycling a fluid between liquid and gaseous phases.

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.

Genetically modified viruses can help construct battery electrodes

MIT scientists' modifications caused the viruses to attract conductive materials, such as gold ions, which the viruses self-assembled into nanowires that could be used in batteries. These components allow batteries to be thinner and flexible enough to be constructed into new shapes.

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.

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.

The Higgs boson provides a mechanism that explains why some particles have mass

The mathematics of quantum field theory suggested that force particles should be massless, like the photon for electromagnetism, but the weak nuclear force’s equivalent W and Z particles are not. The Higgs field provides mass when interacting with such particles.

How helium enables MRI machines to look inside organisms

By cooling the machine's magnets with liquid helium to extremely low temperatures, they can generate and maintain powerful magnetic fields that align the hydrogen atoms in living things to point toward a patient's head or feet. A radio pulse nudges these atoms, which realign and induce a measurable signal in nearby electrical coils. These signals are captured in slices and then stacked into a 3D reconstruction.

A battery management system determines the displayed battery percentage

The software in modern devices provides values by combining estimates based on voltage—akin to knowing how much air is left in a tire based on the pressure of the escaping air—and coulomb counting, where the rate of electrical current is calibrated to the ratio of remaining charge to full capacity.

Lightning forms when streams of rising and falling charged particles connect

In cloud-to-ground lightning, a buildup of negative charge at the bottom of clouds repels electrons on Earth's surface, leaving behind positively charged particles. When descending negatively charged air—the stepped leader—meets rising positively charged particles—the upward streamer—brightening runs up the connection, producing intense flashes known as return strokes.

Despite electric usage concerns, EV charging accounts for less than 1% of grid load

Other popular myths about EVs include battery failure concerns—failure rates are less than 1% on newer models—and that there are no places to charge cars, though both at-home outlets and more than 77,000 stations on the road are available.

Scientists have diverted the path of lightning using lasers

A proof of concept for a laser protection system, which could be used to protect launchpads and airports in the future, was conducted on the Säntis mountain in northeastern Switzerland. Rapid laser pulses heated air molecules, creating a more conductive, 50-meter (164-foot) path for the electrical discharge to travel through.

Gradual chemical build-up reduces the effectiveness of rechargeable batteries

During charge cycles, small chemical deposits gradually form a film on the electrodes where they make contact with the electrolyte, trapping ions that would otherwise facilitate the flow of electricity. Mechanical degradation from electrode wear and electrical shorting from structural instability can also reduce battery capacity.

Battery and plug-in hybrid EVs can operate with zero tailpipe emissions

Battery electric vehicles only run on electricity, while plug-in hybrids incorporate a small internal combustion engine that recharges the battery or directly powers the wheels to improve driving range. Fuel cell electric vehicles convert hydrogen gas fuel into electricity.