100 Fun Facts About Electricity

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

William Gilbert coined 'electricus' in 1600 for the way rubbed amber attracts light objects; Thales had noted the effect around 600 BCE.

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

Before Gilbert, electricity had been little more than a curiosity for two thousand years.

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

Sparks jumping from the key to his hand showed lightning was electrical; his son William reportedly helped, and the key was borrowed from Benjamin Loxley.

A scientist attempting to replicate Franklin's experiment in St Petersburg in 1753 was killed. Who?

He is thought to have been struck by ball lightning; Dalibard had safely done the rod version in France a month before Franklin's kite.

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

His 'animal electricity' theory was challenged by Volta, but it gave us the words galvanise and galvanic and inspired Mary Shelley's Frankenstein.

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

It gave scientists a steady current for the first time and proved electricity could be made chemically; Napoleon was an admirer.

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

He held the chair of experimental physics at Pavia for nearly forty years, and the volt is named after him.

In 1820 Hans Christian Ørsted noticed, while preparing a lecture, that an electric current did what?

The accidental discovery linked electricity and magnetism; Ørsted was also the discoverer of aluminium and a friend of Hans Christian Andersen.

Michael Faraday invented the electric motor in which year?

A former bookbinder's apprentice hired by Humphry Davy, he went on to discover electromagnetic induction, the basis of every generator.

Which everyday electrical terms did Faraday help popularise?

He also discovered benzene, built an early Bunsen burner and had Einstein's admiration; the farad, the unit of capacitance, bears his name.

Ohm's law is usually written as V = IR. What does the R stand for?

Georg Ohm published his analysis in 1827; current is directly proportional to voltage in a well-behaved conductor.

The ampere is named after a physicist from which country?

André-Marie Ampère is considered a father of electromagnetism alongside Ørsted; since 2019 the amp has been defined by fixing the elementary charge.

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

Watt also developed the concept of horsepower; the unit was adopted by the British Association in 1889 and by the SI in 1960.

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

His equations remain the basis of all modern electromagnetic theory; Einstein kept his portrait beside Faraday's and Newton's.

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

Franklin set the convention long before electrons were discovered, so 'conventional current' runs opposite to the actual electron flow.

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

The name 'electron' had already been proposed by George Johnstone Stoney in the 1870s and 1890s.

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

That is why an electrical signal reaches the far end of a cable almost instantly even though individual electrons crawl.

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

Copper's softness partly explains its conductivity; it is used for most wiring because silver is far too expensive.

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

Rubbing transfers electrons between materials; a balloon rubbed on hair goes negative and clings to a wall.

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

That sudden heating creates the shock wave we hear as thunder.

Roughly how many lightning flashes occur on Earth per second, on average?

That works out to nearly 1.4 billion flashes a year; Lake Maracaibo in Venezuela sees the most, with about 250 bolts a day.

Where on Earth does lightning occur most often, with the Catatumbo phenomenon producing about 250 bolts a day?

Most cloud-to-ground strikes are 'negative'; positive flashes make up under 5% but are more powerful.

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

Despite the name they are knifefish, not true eels; in 2019 they were split into three species, one named Electrophorus voltai after Volta.

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

It began with six 100 kW dynamos serving 400 lamps for 82 customers in Manhattan's financial district and ran the world's first underground urban network.

How many US patents did Thomas Edison register?

The 'Wizard of Menlo Park' ran what is considered the first industrial research laboratory and became deaf as a child.

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

His November 1879 patent listed cotton, linen and wood splints; Joseph Swan's bulbs were already lighting London by 1881, and tungsten came later.

Roughly what share of the energy an incandescent bulb uses becomes visible light?

The rest is heat, which is why LEDs have taken over most of the market.

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

His company licensed Tesla's induction motor patents in 1888 and won the contract to light the 1893 Chicago World's Fair.

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

Edison Electric merged with Thomson-Houston, effectively ending the war of the currents; the last DC utility in New York City was not switched off until 2007.

Nikola Tesla was born in 1856 in Smiljan, a village in what is now which country?

An ethnic Serb, he briefly worked for Edison in New York before licensing his AC patents to Westinghouse.

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

His work had fallen into obscurity after his death in a New York hotel in 1943; his unfinished Wardenclyffe Tower was meant to transmit power wirelessly.

Tesla built one of the first wirelessly controlled vehicles ever produced. What was it?

He demonstrated it in 1898; he also experimented with X-ray imaging and dreamed of worldwide wireless power from Colorado Springs.

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

Heike Kamerlingh Onnes made the discovery in Leiden; 'high-temperature' ceramic superconductors followed in 1986.

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

Tokyo is on 50 Hz and Osaka on 60 Hz, a legacy of buying German and American generators in the 1890s.

Standard household outlets in North America supply roughly what voltage?

The split-phase system also offers 240 V for big appliances; the low voltage is one reason electric kettles are rare in the US.

The Northeast blackout of August 2003 left about how many people without power?

A software bug in FirstEnergy's Ohio control-room alarm system meant operators did not see overloaded lines sagging into trees.

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

It straddles the Nevada-Arizona border and created Lake Mead; Franklin Roosevelt dedicated it in September 1935.

Which pair discovered in 1800 that current from a voltaic pile could split water?

Faraday greatly extended the work in 1833 and formulated the laws of electrolysis.

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

Joule heating is what makes toasters, kettles and incandescent bulbs work.

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

Coulomb's law gives the inverse-square force between charges; one amp is one coulomb of charge per second.

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

Its time-averaged value is zero, yet it delivers energy first one way then the other; batteries and most electronics use direct current instead.

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 former Edison employee patented an improved way of making carbon filaments in 1882?

The African American inventor's process was bought by the United States Electric Light Company and gave rival Maxim bulbs their distinctive M-shaped filaments.

Which Greek philosopher studied static electricity by rubbing amber rods around 600 BCE?

He wrongly believed the friction made the amber magnetic, like the mineral magnetite.

How did Benjamin Franklin fund his extensive electrical research?

His June 1752 kite experiment reputedly showed sparks jumping from a key to the back of his hand.

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

By modern convention electrons are negative and protons positive, each carrying exactly the elementary charge.

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.

Piezoelectricity, in which pressed crystals such as quartz generate a voltage, was discovered in 1880 by whom?

The effect works in reverse too: an electric field makes the material change size slightly. Even sugar is piezoelectric.

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

Sharks, by contrast, are electroreceptive: they detect electric fields rather than generate them as weapons.

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

The field inside is therefore zero, which is the operating principle of the Faraday cage.

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.