Light Bulb Trivia
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89 free Light Bulb trivia questions with answers — technology quiz, new questions added Oct 2026.
The light bulb is the classic symbol of a bright idea, and its real history is far messier than the Edison legend. This quiz covers the whole story: Humphry Davy's glowing platinum strip in 1802, the forgotten patents of the 1840s, Joseph Swan's Newcastle demonstrations, Edison's bamboo filament and his integrated lighting system, Lewis Latimer's carbon process, the switch to tungsten and inert gas, the cartel that fixed bulb life at 1,000 hours, the fire-station bulb that has burned since 1901, and the modern age of halogen, fluorescent, sodium, neon and LED lighting up to the Nobel Prize for the blue LED and the bans on incandescents. Easy questions ask what a filament is made of and who founded Menlo Park; harder ones cover the Hungarian tungsten patent, the E in E27 and how much of a bulb's energy becomes light. It suits science and technology students, engineers, history buffs and quiz nights that want a science round rooted in everyday objects. Every answer has been checked against the Wikipedia articles on incandescent, fluorescent, halogen and LED lighting and the people behind them, and each question shows its source once you have answered.
30 of 89 questions with answers and explanations. Play the quiz
Q 01How does an incandescent light bulb produce light?
By heating a filament until it glows
By heating a filament until it glows: in open air the white-hot wire would burn out almost at once, which is why it has to be sealed inside the glass bulb.
Q 02Which toy, launched by Kenner in 1963, was powered by two ordinary 100-watt light bulbs?
Easy-Bake Oven
Easy-Bake Oven cakes cooked on waste warmth, since an incandescent bulb gives off far more heat than light; Kenner chose bulbs over a heating element to calm fears of burnt fingers.
Q 03Which unit, printed on modern bulb packaging, measures how much light a lamp actually gives off?
Lumens
Lumens count the light itself, while watts only measure the power drawn, so wattage stopped being a guide to brightness once far more efficient lamps arrived.
Q 04In the early 1800s Humphry Davy made incandescent light by passing current through a strip of which costly metal?
Platinum
Platinum glowed when Davy ran current through a thin strip of it, but the strips soon failed, and it took other experimenters more than 75 years to turn the idea into a practical bulb.
Q 05Which electric light, shown by Humphry Davy in the early 1800s, proved so bright it suited lighthouses rather than homes?
The carbon arc lamp
The carbon arc lamp made its light from a spark leaping between two carbon rods, so fierce and power-hungry that it stayed in railway stations, big stores and other large spaces.
Q 06Before electric spotlights, nineteenth-century theatres lit their stars by heating a block of which substance until it glowed?
Quicklime
Quicklime glowing in a jet of burning oxygen and hydrogen was the original limelight, which is why anyone at the centre of public attention is still said to be in it.
Q 07Which country's official citizenship guide credits Mathew Evans and Henry Woodward, not Edison, with inventing the light bulb?
Canada
Canada's guide says the pair, who built their lamp in Toronto and patented it in 1874, invented the first electric light bulb and then sold the patent to Edison, who made it famous.
Q 08Joseph Swan began experimenting in 1850 with filaments made from what, sealed in an evacuated bulb?
Carbonised paper
Carbonised paper burned out fast in the poor vacuums of the 1850s, so Swan's lamp stalled for years until better pumps let him return to it in the 1870s.
Q 09Which London playhouse became the first public building lit entirely by electricity in 1881?
The Savoy
The Savoy's manager, Richard D'Oyly Carte, showed the audience the lamps were safe by wrapping one in muslin and breaking it on stage: it went out without even singeing the cloth.
Q 10The first street in the world lit by incandescent bulbs was Mosley Street, in which English city where Joseph Swan worked?
Newcastle upon Tyne
Newcastle upon Tyne was Swan's proving ground: he showed his lamp to 700 people at its Literary and Philosophical Society in February 1879, and the same lamps lit Mosley Street.
Q 11Edison's breakthrough lamp of October 1879 burned for over half a day on a carbonised filament of what?
Cotton thread
Cotton thread, the ordinary sewing kind baked to carbon, gave Edison his first lamp that lasted; accounts put the run at 13.5 or 14.5 hours, and within a year his filaments were lasting hundreds.
Q 12Which plant material did Edison's team discover made a filament lasting over 1,200 hours?
Carbonised Japanese bamboo
Carbonised Japanese bamboo won out after months of further trials, with Edison sending men abroad to find the best stems, and it stayed his standard filament for about ten years.
Q 13What was the first commercial application of Edison's incandescent lamps, in 1880?
Q 21In 1913 Irving Langmuir found that filling a bulb with what, instead of a vacuum, doubled its efficacy?
An inert gas such as argon
An inert gas such as argon went against his colleagues' hunch that a better vacuum was the answer: the gas slowed the tungsten boiling off the filament and blackening the glass.
Q 22Marvin Pipkin's 1925 patent for General Electric solved which light-bulb problem?
Frosting a bulb's inside without weakening it
Frosting a bulb's inside without weakening it mattered because earlier acid-etched bulbs turned brittle and broke in ordinary handling; his finish softened the bare filament's glare and stayed strong.
Q 23The Phoebus cartel of 1925–1939 is commonly cited as an early example of what?
A steamship, the Columbia
A steamship, the Columbia, came first because her owner Henry Villard saw Edison's New Year's Eve demonstration and insisted on the lights for his new ship, despite Edison's own reluctance.
Q 14Historians credit Edison's success over rival bulb-makers less to his lamp than to what?
Building a whole lighting system
Building a whole lighting system set Edison apart: he supplied the generators, mains and wiring too, while rivals with lamps just as good had no network to plug them into.
Q 15Which Black American inventor patented an improved process for making carbon filaments in 1882?
Lewis Latimer
Lewis Latimer had already made his mark as a draftsman: in 1876 he drew the patent drawings for Alexander Graham Bell's telephone, before turning to electric light.
Q 16The name 'tungsten', the metal in most bulb filaments, comes from Swedish words meaning what?
Heavy stone
Heavy stone is the literal Swedish, but German speakers call the same metal wolfram, which is why its chemical symbol is W rather than T.
Q 17What did research published in 2007 conclude about Heinrich Göbel's claim to have built a light bulb in 1854?
The story is fictitious
The story is fictitious, the study found: the claim was pressed in 1893 as a courtroom defence for lamp makers Edison's company was suing, and the patent expired before any final ruling.
Q 18Sándor Just and Franjo Hanaman's tungsten filament of 1904 was put on sale by Tungsram, a company from which country?
Hungary
Hungary's Tungsram, based in Budapest, put the lamp on the market; its tungsten wire burned brighter and lasted longer than carbon, the biggest change to the bulb since Edison.
Q 19After making tungsten workable for bulb filaments, William Coolidge invented the modern what?
X-ray tube
X-ray tube: he put his workable tungsten into that too, and the Coolidge tube soon replaced earlier designs and became the pattern for the X-ray tubes made since.
Q 20Why is tungsten the ideal filament metal?
It has the highest melting point of any metal
It has the highest melting point of any metal, above 3,400 °C, so a tungsten filament can glow white-hot for hundreds of hours without melting.
Planned obsolescence
Planned obsolescence: Osram, Philips and the other members agreed to cap bulb life at 1,000 hours, had sample lamps tested, and fined any factory whose bulbs burned longer.
Q 24The Phoebus cartel was incorporated in which city in January 1925?
Geneva
Geneva was where the lamp makers met in December 1924 and set up Phoebus S.A. weeks later; the pact was meant to run until 1955 but fell apart when war broke out in 1939.
Q 25The Centennial Light, a bulb burning almost continuously since 1901, hangs in a fire station in which California city?
Livermore
Livermore gave the bulb a full police and fire-truck escort when its firehouse moved in 1976, and since then it has run on its own protected power supply.
Q 26After more than a century, the Centennial Light, once a 60-watt bulb, glows about as brightly as what?
A 4 W nightlight
A 4 W nightlight is about its level now; when its backup power failed in 2013, viewers on its webcam thought it had finally burned out, but it came back on.
Q 27In the Edison screw designation E27, what does the number stand for?
The base diameter in millimetres
The base diameter in millimetres, so an E27 cap is 27 mm across; the E is for Edison, whose screw fitting beat the incompatible bases of rival lamp makers to become the standard.
Q 28A halogen lamp is a tungsten-filament bulb whose gas fill contains a small amount of which elements?
Iodine or bromine
Iodine or bromine vapour catches the tungsten that boils off the filament and carries it back, so the lamp can run hotter and brighter without its glass blackening.
Q 29Halogen lamp capsules run so hot they are often made of what instead of ordinary glass?
Quartz
Quartz can take the heat, but oil from a fingertip leaves a hot spot that can crack it, which is why you are told never to handle a halogen bulb with bare hands.
Q 30In fluorescent lighting, glowing mercury vapour gives off what, which a coating on the glass then turns into visible light?
Ultraviolet
Ultraviolet is invisible, so the phosphor coating soaks it up and glows white; the same lamp made without the coating, in glass that lets the rays out, is a germicidal lamp for killing bacteria.