100 Fun Facts About Electricity

The word 'electricity' derives from 'elektron', the ancient Greek word for what?

Amber rubbed with fur attracts small objects such as feathers, an effect noticed in ancient Greece, so its Greek name was borrowed in 1600 for the new science of electricity.

Whose 1600 book De Magnete first carefully separated static electricity from magnetism?

William Gilbert, later physician to Elizabeth I, built the versorium, a pivoting pointer that could detect electric charge, and argued that the Earth itself is one great magnet.

Benjamin Franklin is said to have flown a kite in a storm in June 1752 with what tied to the string?

A metal key hung from the kite string; by Joseph Priestley's later account, Franklin saw the loose threads of the string stand on end and drew a spark from the key with his knuckle.

Which physicist was killed in St Petersburg in 1753 while trying a version of Franklin's lightning experiment?

Georg Wilhelm Richmann was watching his apparatus during a storm when a discharge, reported to be ball lightning, struck his head; he is thought to be the first person killed in electrical research.

Luigi Galvani discovered in 1780 that the legs of dead frogs did what when touched by an electric spark?

The legs twitched as if alive, which Galvani put down to 'animal electricity'; talk of such sparks reviving the dead is said to have helped inspire Mary Shelley's Frankenstein.

Volta's 1800 voltaic pile was made from alternating discs of copper and which other metal?

Zinc and copper discs were stacked with brine-soaked card between each pair; Napoleon was so taken with Volta's demonstration of the pile in Paris that he later made him a count.

Besides inventing the battery, Volta is credited with discovering which gas?

Methane was the gas Volta collected in 1776 from bubbles rising out of the marshy shallows of Lake Maggiore; he then showed that an electric spark could set it alight.

In 1820 Hans Christian Ørsted found that switching on an electric current did what?

Deflected a compass needle: the swing was the first proof that electricity and magnetism are linked, and within weeks it set Ampère working out the mathematics of the force.

Michael Faraday began his working life as an apprentice in which trade?

Bookbinding let Faraday read the books that passed through the shop; he then sent Humphry Davy a bound copy of his notes on Davy's lectures and won a job as his assistant.

Which everyday electrical terms did Faraday help popularise?

Anode, cathode, electrode and ion reached print through Faraday in 1834; he had asked the scholar William Whewell, who also coined 'scientist', to devise most of them.

In Ohm's law, written V = IR, what does the R stand for?

Resistance is measured in ohms, after Georg Ohm, who worked the law out in the 1820s as a schoolteacher, experimenting in the physics laboratory of the Cologne school where he taught.

The ampere is named after a physicist from which country?

France: Ampère, a mathematical prodigy from Lyon, lost his father to the guillotine in the Revolution, then in 1820 worked out how wires carrying currents attract and repel each other.

The SI unit of power, the watt, honours James Watt for his improvements to what?

The steam engine wasted much of its steam reheating a cylinder that was cooled on every stroke; Watt's separate condenser kept the cylinder hot, so far less coal was burned.

James Clerk Maxwell definitively linked electricity, magnetism and what else in the 1860s?

Light turned out to be an electromagnetic wave, and Maxwell's theory predicted invisible waves of the same kind, which Heinrich Hertz first produced in the 1880s: radio waves.

By historical convention, electric current is defined as flowing in which direction?

From positive to negative: Franklin fixed the labels long before the electron was discovered, so in a metal wire the charges that really move travel the opposite way.

The electron was discovered in 1897 by which physicist, working with cathode rays?

J.J. Thomson won the 1906 Nobel Prize after showing the electron to be a particle; his son George shared the 1937 prize for showing that electrons also behave as waves.

The electric field driving electrons through a wire propagates at close to what?

The speed of light is nearly matched by the signal, so a lamp answers its switch at once, yet the electrons themselves drift along the wire at only a fraction of a millimetre a second.

Among pure metals at room temperature, which alone conducts electricity better than copper?

Silver is the best electrical conductor of all the metals, but only slightly better than copper and far more expensive, so copper does the wiring and silver is kept for small electronic parts.

What is the name for charge transfer through rubbing, which explains static shocks from doorknobs?

The triboelectric effect moves electrons between surfaces that touch and part: a balloon rubbed on hair picks up extra electrons, which is why it will then cling to a wall.

The air around a lightning flash heats to roughly what temperature?

About 30,000 °C, roughly five times hotter than the surface of the Sun; the air expands so violently that it sends out the shock wave we hear as thunder.

Satellite counts put the number of lightning flashes on Earth each second at roughly what?

About 44 flashes a second, or nearly 1.4 billion a year, is the tally from satellite sensors; it replaced an estimate of 100 a second, made in 1925, that had stood for decades.

Which place has the highest lightning rate on Earth, thanks to the Catatumbo storms?

Lake Maracaibo, Venezuela: at night, mountain breezes off the Andes meet warm, moist air over the lake and set off storms, a pattern that knocked the Congo Basin off the top spot.

Electric eels can deliver shocks of up to roughly how many volts?

Up to 860 volts was recorded in 2019 from a newly recognised species named after Volta; despite the name, electric eels are knifefish, not true eels.

Thomas Edison's first commercial power plant, Pearl Street Station, opened in 1882 in which city?

New York's Pearl Street Station lost all but one of its dynamos to a fire in 1890; the survivor is now a museum piece in Michigan.

Edison's first patent covered a machine that recorded what?

Votes: the electric vote recorder, meant for legislatures, was a commercial failure, and Edison resolved from then on to invent only things he was sure people would want.

Edison's team found a carbonised filament of which material could burn for about 1,200 hours?

Japanese bamboo far outlasted the carbonised cotton thread of Edison's first successful lamp, which had burned out in under 15 hours, and it stayed his standard filament for about ten years.

An old-style incandescent bulb turns most of the electricity it uses into what?

Heat takes at least 90% of the power, because a filament has to glow white-hot to shine at all; that waste is why LED lamps have largely replaced the incandescent bulb.

In the 'war of the currents', which industrialist backed AC against Edison's direct current?

George Westinghouse, inventor of the railway air brake, bought Tesla's AC motor patents and went on to illuminate the 1893 Chicago World's Fair with alternating current.

The 1892 merger of Edison's company with its biggest rival created which corporation?

General Electric was born when the banker J.P. Morgan helped merge Edison General Electric with Thomson-Houston; the new company dropped Edison's name.

Nikola Tesla, an ethnic Serb, was born in 1856 in Smiljan, a village now in which country?

Croatia: Smiljan was then part of the Austrian Empire. Tesla's father, an Orthodox priest, wanted him to join the clergy but promised him engineering school if he survived a bout of cholera.

The tesla, named in Nikola Tesla's honour in 1960, is the SI unit of what?

Magnetic flux density is the strength of a magnetic field; a hospital MRI scanner's field, a few teslas, is strong enough to drag phones and even oxygen tanks towards the machine.

Which kind of vehicle did Nikola Tesla steer by radio control at Madison Square Garden in 1898?

A boat: Tesla hoped to sell the idea to the US military, but it showed little interest.

Superconductivity was discovered in 1911 in which element cooled by liquid helium?

Mercury abruptly began to carry current with no loss at all, about four degrees above absolute zero, in the laboratory of Heike Kamerlingh Onnes, who had earlier been the first to liquefy helium.

Which country runs its power grid on two different frequencies, 50 Hz in the east and 60 Hz in the west?

Japan's split dates from the 1890s, when Tokyo bought German 50 Hz generators and Osaka American 60 Hz ones; it left the west able to send the east very little power after the 2011 tsunami.

Standard household outlets in North America supply roughly what voltage?

120 V is half of the 240 V supply that reaches most North American homes on two live wires; ovens and clothes dryers connect across both wires to get the full 240 V.

The 2003 Northeast blackout, which cut power to some 50 million people, spread into which Canadian province?

Ontario lost power along with eight US states after overloaded lines in Ohio sagged into trees and a software bug kept the control-room alarms from warning operators in time.

The Hoover Dam, built between 1931 and 1936, sits on which river?

The Colorado River dam stands in Black Canyon, not the Boulder Canyon named in the act that funded it, and was widely called Boulder Dam until Congress settled on Hoover Dam in 1947.

What is the process of splitting water with an electric current, done with a battery by Nicholson and Carlisle in 1800, called?

Electrolysis by battery began weeks after Volta announced his pile, when William Nicholson and Anthony Carlisle built one of their own and found its current split water into hydrogen and oxygen.

Which English physicist, remembered in the unit of energy, studied resistive heating of wires in 1840?

James Prescott Joule, son of a wealthy Salford brewer, pursued science alongside the family brewery; the heating he measured is what makes toasters and electric kettles work.

The unit of electric charge honours which 18th-century French physicist?

Coulomb, a French military engineer, measured the force between charges with a torsion balance he invented, in which a twisting fibre registered pushes far too faint to weigh.

Alternating current reverses direction repeatedly, almost always following what waveform?

A sine wave comes naturally from a generator: a coil turning steadily in a magnetic field produces a voltage that rises and falls with the sine of the coil's angle.

Humphry Davy made an early incandescent light in 1802 by passing current through a strip of which metal?

The battery had 2,000 cells in the basement of the Royal Institution; platinum was chosen for its very high melting point.

Which Black inventor patented a better way to make carbon filaments in 1882?

Lewis Latimer had earlier made the patent drawings for Bell's telephone; he joined Edison's company in the mid-1880s and defended its lamp patents as an expert witness.

Which Greek philosopher is credited with the earliest observations of static electricity, around 600 BCE?

Thales of Miletus is also said to have foreseen a bumper olive harvest and rented every press in advance, to show that a philosopher could get rich if he chose.

Benjamin Franklin could afford years of electrical experiments after retiring in his early forties from which business?

A printing house: Franklin handed the running of the shop to his foreman David Hall and kept drawing a share of its profits, an income that freed him for science and public service.

Franklin defined positive charge as the charge acquired by a glass rod rubbed with what?

A silk cloth and the glass rod end up with equal and opposite charges; Franklin, who pictured electricity as a single fluid, labelled the glass positive long before electrons were known.

Roughly what current is the threshold for a person to perceive mains-frequency electricity?

Under some conditions a current as low as a microamp can be felt as an electrovibration effect.

Pierre Curie discovered piezoelectricity in 1880, years before he met Marie, working with which collaborator?

His brother Jacques shared the discovery that squeezed quartz produces a voltage, the effect that now keeps time in quartz clocks and watches.

Modified muscle cells that let electric eels generate high voltages are called what?

Electrocytes are stacked in columns like the discs of a battery, a likeness Volta drew himself: his 1800 letter compared the first pile to the electric organ of the torpedo ray.

Where does a hollow conducting body carry all of its electric charge?

On its outer surface, which leaves no electric field inside: that is why the metal shell of a car or an airliner shields the people in it when lightning strikes.

Benjamin Franklin badly shocked himself while trying to kill which bird with electricity for a dinner party?

A turkey was the planned main course, to be roasted on an electrical spit. Franklin's arms stayed numb all evening, and he called the mishap a 'Notorious Blunder'.

Talk of galvanism, the hope that electricity might reanimate a corpse, helped inspire which novel published in 1818?

Frankenstein began in 1816 as Mary Shelley's entry in a ghost-story contest proposed by Lord Byron. 'Perhaps a corpse would be re-animated,' she later wrote of the idea.

Older strings of Christmas tree lights go completely dark when one bulb burns out because the bulbs are wired how?

In series means the current has only one path, through every bulb in turn, so a single dead filament breaks the whole loop. Modern strings add a tiny shunt that bridges a failed bulb.

Britain's power grid braces for a sudden surge when big TV shows end because millions of viewers switch on what?

Kettles boiled for tea cause the surge, known as TV pickup. The biggest on record followed England's 1990 World Cup semi-final shootout, and grid staff still study TV schedules to prepare.

The word 'electrocution', coined in the United States in 1889, blends 'electro' with which other word?

Execution by electric chair was all the word meant when American newspapers coined it in 1889. Only later did it stretch to cover accidental deaths.

Gel-filled pores called ampullae of Lorenzini let which fish sense the faint electric fields given off by hidden prey?

Sharks are more sensitive to electric fields than any other animal, able to pick up the tiny signals from a hidden fish's muscle contractions. The pores cluster around the snout and mouth.

Which metal, the least dense of all, gives its name to the rechargeable batteries in most phones and electric cars?

Lithium floats on water, and batteries built around it store so much energy for their weight that three of their developers shared the 2019 Nobel Prize in Chemistry.

Which device, invented by William Sturgeon in the 1820s, lets scrapyard cranes pick up and drop tons of iron?

An electromagnet is magnetic only while current flows through its coil, so a crane drops its load at the flick of a switch. Sturgeon's first weighed seven ounces yet lifted nine pounds.

Which London power station has an inflatable pig floating between its chimneys on the cover of Pink Floyd's Animals?

Battersea burned coal beside the Thames until 1983 and is one of the largest brick buildings in the world. Its restored shell opened to the public in 2022.

Which island nation generates virtually all of its electricity from hydropower and geothermal heat?

Iceland gets about 70% of its electricity from hydropower and nearly all the rest from geothermal plants. The same volcanic heat warms nine in ten Icelandic homes.

Which device, two coils of wire wound on a shared iron core, raises or lowers the voltage of alternating current?

A transformer lets the grid carry power at very high voltages, which wastes far less energy as heat in the wires, and then steps it back down for homes.

The Leyden jar, invented in the 1740s to store electric charge, was the earliest form of which circuit component?

The capacitor began as a water-filled glass jar that could hold a charge and release it in one jolt. Benjamin Franklin wired several capacitors together and called the set an 'electrical battery'.

Which component, invented at Bell Labs in 1947, replaced the bulky vacuum tube and made pocket electronics possible?

The transistor won John Bardeen, Walter Brattain and William Shockley the 1956 Nobel Prize in Physics. A single modern microprocessor can hold tens of billions of them.

Wireless charging pads and electric toothbrush stands pass power to a device without metal contacts using which effect?

Induction uses a coil in the pad to create a changing magnetic field, which drives a current in a second coil inside the device. Michael Faraday discovered the effect in 1831.

Household electricity meters and utility bills record the energy a home has used in which unit?

Kilowatt-hours measure energy, not power: one is what a 1,000-watt heater uses in an hour. A typical home runs through a few hundred to a few thousand of them every month.

Which capital Greek letter is the symbol for the ohm, the electrical unit named after Georg Ohm?

Omega stands for the ohm, and turning the letter upside down gave the symbol for an older unit, the mho, whose name is simply 'ohm' spelled backwards.

Which metal, with the highest melting point of any metal, forms the glowing filament in an incandescent bulb?

Tungsten stays solid up to 3,422 °C, so a filament made of it can glow white-hot without melting. Its chemical symbol, W, comes from its German name, Wolfram.

The 2014 Nobel Prize in Physics honoured the inventors of an efficient blue version of which lamp technology?

The LED could glow white only after Isamu Akasaki, Hiroshi Amano and Shuji Nakamura built bright blue ones in the early 1990s, since white needs red, green and blue mixed together.

Which eerie blue glow appears on ships' masts and aircraft windshields when thunderstorms charge the air around them?

St. Elmo's fire is a corona discharge: a strong electric field turns the air around a pointed object into glowing plasma. It is named after Erasmus of Formia, the patron saint of sailors.

Samuel Morse sent 'What hath God wrought' from Washington to Baltimore in 1844 using which electrical invention?

The telegraph put electricity to work carrying news, sending Morse's dots and dashes down a wire in an instant. Within two decades its lines had spread across the United States.

Which English chemist lit his Gateshead home with incandescent bulbs and later merged his lamp company with Edison's?

Joseph Swan showed his carbon lamp in Newcastle in 1878, and his bulbs lit London's Savoy Theatre in 1881. The two rivals' British firms merged into a company nicknamed 'Ediswan'.

Thomas Edison built the first industrial research laboratory in 1876 in which New Jersey community?

Menlo Park earned Edison the nickname 'The Wizard of Menlo Park'. When he arrived it was a failed housing development, named after a town in California.

Which American tycoon gave Nikola Tesla $150,000 to build his giant wireless tower at Wardenclyffe on Long Island?

J. P. Morgan paid for a transatlantic radio station, but Tesla enlarged the plan to send power through the Earth as well and ran out of money. The tower was demolished for scrap in 1917.

Which US president had electricity installed in the White House but was too afraid of shocks to touch the switches?

Benjamin Harrison and his wife feared electrocution so much that they often went to sleep with the lamps still on. Edison's company had wired the building for them.

The stun weapon Taser takes its name from which fictional boy inventor's 'Electric Rifle' in a 1911 novel?

Tom Swift was the childhood hero of the Taser's inventor, Jack Cover, who finished the device in 1974. The 1911 adventure was titled 'Tom Swift and His Electric Rifle'.

The Three Gorges Dam, the largest power station on Earth by capacity, spans which river in central China?

The Yangtze drives turbines with a combined capacity of 22,500 megawatts. The dam was also built to hold back floods and to help ships travel further upstream.

A solar storm in March 1989 blacked out which Canadian province's entire power grid in under two minutes?

Quebec lost power for nine hours after swings in Earth's magnetic field tripped circuit breakers on Hydro-Québec's very long transmission lines.

Willem Einthoven won the 1924 Nobel Prize in Medicine for a machine recording the electrical activity of which organ?

The heart gives off a tiny electrical pulse with every beat, and Einthoven's electrocardiograph traced it on paper. His labels for the waves, P, Q, R, S and T, are still in use.

Roman physician Scribonius Largus prescribed shocks from which living sea creature to treat headaches and gout?

A torpedo fish is an electric ray, and Scribonius wrote up the cure in the first century AD, long before anyone understood electricity. The naval weapon takes its name from the same fish.

What name, from the Latin for lightning, is given to the glassy tubes formed when a bolt strikes sand?

Fulgurite is nicknamed 'fossilized lightning': the strike melts the sand along its path and leaves behind a hollow, branching tube of glass.

Rubber, glass and most plastics, used to coat wires and hold up power lines, belong to which class of materials?

Insulators hold their electrons too tightly for a current to flow easily. Even so, every one of them breaks down and conducts if the voltage across it climbs high enough.

Turning a lamp switch off separates its contacts and leaves the circuit in which state, carrying no current?

Open means there is a gap in the path, so nothing flows, which is the reverse of a door or a tap. Closing the switch brings the contacts together and completes the loop.

Which safety device, patented by Thomas Edison in 1890, uses a thin metal strip that melts when current runs too high?

A fuse is a sacrificial device: once its strip has melted, the current stops and the fuse has to be replaced or rewired before the power comes back.

The round third pin on a North American plug links an appliance's metal case to which wire?

Ground connects first, because its pin is made slightly longer than the two flat blades. If a fault electrifies the case, the stray current then has a safe path away from the user.

Which lightweight metal, rather than copper, carries the current in most long-distance overhead power lines?

Aluminium is chosen for its low weight, low cost and good conductivity. The usual cable wraps strands of it around a steel core, which adds the strength to span the gap between pylons.

Which heavy metal forms the plates of the rechargeable battery that starts most petrol and diesel cars?

Lead plates in acid made the first rechargeable battery, invented by Gaston Planté in 1859. Cars still rely on it because it can supply the burst of high current a starter motor needs.

Albert Einstein's 1921 Nobel Prize rewarded his explanation of which phenomenon, rather than his theory of relativity?

The photoelectric effect is the release of electrons from a material struck by radiation such as ultraviolet rays. Einstein showed the energy arrives in separate packets, a founding idea of quantum physics.

Georges Claude's neon tubes, shown at the 1910 Paris Motor Show, glowed which colour, the only one pure neon gives?

Reddish-orange is the only colour pure neon gives off. Signs in other colours hold a different gas, such as argon, or use tubes lined with a glowing coating called a phosphor.

Which electrical unit takes its name from an English scientist who started out as a bookbinder's apprentice?

The farad honours Michael Faraday and measures how much charge a component can store. It is so large that real parts are usually rated in millionths or billionths of one.

Which element, the second most abundant in Earth's crust, is the main material in most solar panels?

Silicon makes up about 28% of Earth's crust by mass, bound up in sand and rock. Only oxygen is more plentiful, yet solar cells need it refined to extreme purity.

Otto von Guericke built an early static electricity machine around 1663 from a hand-rubbed globe of which element?

Sulphur made a globe that could be turned and rubbed by hand until it drew small objects towards it. Isaac Newton later built his own machine with a glass globe instead.

Humphry Davy used a voltaic pile to isolate which element, the first metal ever obtained by electrolysis?

Potassium came out of caustic potash once Davy passed electricity through it. He isolated sodium the same year, 1807, then calcium, strontium, barium and magnesium the year after.

Which electrical unit honours the American scientist who became the Smithsonian Institution's first secretary?

The henry honours Joseph Henry, who built a forerunner of the electric doorbell in 1831 and invented the relay in 1835, then ran the Smithsonian for more than thirty years.

Despite its name, the electric eel is not a true eel but belongs to which South American group of fishes?

Knifefish are mostly weakly electric: they use faint fields to sense their surroundings but cannot deliver a shock. The electric eel is the high-powered exception.

Werner von Siemens's company opened the world's first electric tram service in 1881 in a suburb of which city?

Berlin had already hosted the first electric passenger train, which Siemens presented at an industrial exhibition two years earlier. He built the first electric elevator in between.

Robert Millikan won a Nobel Prize after measuring a single electron's charge using tiny floating droplets of what?

Oil of the kind used in vacuum pumps was chosen because it barely evaporates, so each droplet kept its mass while Millikan balanced gravity against an electric pull.

Which red flashes high above thunderclouds, first photographed in 1989, are named after elusive spirits of folklore?

Sprites were first caught on camera by accident, by University of Minnesota scientists using a sensitive video camera. They are usually triggered by a lightning stroke in the storm below.

Which city's 1893 world's fair, lit by alternating current, dealt Edison's direct current a famous public defeat?

Chicago's organisers picked the alternating-current bid because it undercut the one from Edison's company, and about 27 million people visited the electrified fair.

Which revolutionary leader's famous slogan defined communism as Soviet power plus electrification?

Vladimir Lenin backed the slogan with a plan for a network of 30 regional power plants, which became the prototype for the later Five-Year Plans.

Paraguay shares the giant Itaipu hydroelectric dam on the Paraná River with which other country?

Brazil takes most of the output: Paraguay's half of the generators make more than the country can use, so the surplus is exported straight across the river.