This physics trivia quiz runs 60 free questions with answers across the whole subject: the SI units and who they are named after, the constants that hold the universe together, the classic experiments from Cavendish's torsion balance to the LIGO detectors, and the people behind quantum and particle physics. It starts with things most people half-remember from school, such as the speed of light, absolute zero and why the sky is blue, and climbs to questions for real enthusiasts: which metal superconductivity was first seen in, what is carved on Boltzmann's tombstone, and who quipped 'Who ordered that?' when the muon turned up. It works as a science round for a pub quiz, a classroom warm-up or a solo test of how much physics you actually retained. Every answer has been checked against an encyclopaedia or primary source, and each question shows its explanation and citation once you have answered, so a disputed fact can be settled on the spot.
30 of 60 questions with answers and explanations. Play the quiz
Q 01Roughly how fast does light travel through empty space?
About 300,000 km per second
The exact figure is 299,792,458 metres per second, and the metre itself is now defined from it. That works out to about one billion kilometres per hour.
Q 02Whose three laws of motion were first published in the Principia in 1687?
Isaac Newton
The Principia's full title is Philosophiae Naturalis Principia Mathematica, and it also set out universal gravitation. It was written in Latin.
Q 03Which SI unit, symbolised by the Greek letter omega, measures electrical resistance?
Ohm
It honours the German physicist Georg Ohm, whose law links voltage, current and resistance. Omega was chosen because the letter O was easily confused with zero.
Q 04What phenomenon makes the daytime sky look blue?
Rayleigh scattering
Air molecules scatter short blue wavelengths far more than long red ones. The same effect leaves the low Sun looking orange at twilight once the blue has been scattered away.
Q 05At 20 °C, how fast does sound travel through air?
About 343 metres per second
That is roughly a kilometre every three seconds, which is why you count the seconds between lightning and thunder. In fresh water sound moves more than four times faster.
Q 06Absolute zero corresponds to which temperature on the Celsius scale?
−273.15 °C
It is the point where a gas's pressure and volume would extrapolate to nothing. In 1779 Johann Lambert had already estimated absolute cold at about −270 °C.
Q 07Which SI unit of power is named after a Scottish inventor?
Watt
James Watt improved the steam engine, and Werner von Siemens proposed naming the unit after him. The absolute watt formally joined the SI in 1960.
Q 08Who received the very first Nobel Prize in Physics, in 1901?
Wilhelm Röntgen
He was honoured for discovering X-rays, which are still called Röntgen rays in many languages. He refused to patent the discovery.
Q 09Ignoring air resistance, by roughly how much does a falling object's speed increase each second?
9.8 m/s
The figure is not the same everywhere: it is about 0.5% larger at the poles than at the Equator, so you weigh very slightly more in Helsinki than in Singapore.
Q 10In the name of CERN's Large Hadron Collider, what is a hadron?
A particle made of quarks
Protons and neutrons are the best-known hadrons. The 27 km ring near Geneva is the world's largest and highest-energy particle accelerator.
Q 11Which British physicist is credited with discovering the electron in 1897?
J. J. Thomson
He measured the mass-to-charge ratio of cathode-ray 'corpuscles' and found them about 1,400 times lighter than a hydrogen ion. His son George later won a Nobel for showing electrons behave as waves.
Q 12Which SI unit is defined as one cycle or event per second?
Hertz
It honours Heinrich Hertz, the first person to prove conclusively that electromagnetic waves exist. Like all units named after people, it is lower-case when written out in full.
Q 13In which year did the ATLAS and CMS experiments at CERN announce the discovery of the Higgs boson?
2012
Q 21Which SI unit of energy is named after an English physicist born in 1818?
Joule
James Prescott Joule was a brewer's son who worked out how much mechanical work it takes to heat water. One of these units is the work done pushing with a force of one newton over one metre.
Q 22Which physicist led the first self-sustaining nuclear chain reaction at Chicago Pile-1 in 1942?
Enrico Fermi
The reactor was built under the stands of a disused football stadium at the University of Chicago. Ten days later its output was raised to a mighty 200 watts.
Q 23Which particle did James Chadwick discover in 1932, earning him a Nobel Prize three years later?
The neutron
The announcement came on 4 July, ending a search that had lasted about 40 years. The new particle weighed in at around 125 GeV.
Q 14In which year did Erwin Schrödinger describe his famous cat thought experiment?
1935
It came out of a discussion with Albert Einstein and was meant as a critique of the Copenhagen view of quantum mechanics, not an endorsement of it.
Q 15Whose principle says buoyant force equals the weight of fluid displaced?
Archimedes
The principle is the foundation of fluid mechanics and explains why steel ships float. It does not account for surface tension, which is what lets a needle rest on water.
Q 16Christian Doppler first proposed his famous effect in an 1842 treatise about the coloured light of what?
Binary stars
He was trying to explain star colours, an application that turned out to be wrong, but the effect itself was right and now underpins everything from radar guns to medical ultrasound.
Q 17Which SI unit of pressure is named after a French mathematician who experimented with barometers?
Pascal
It has largely replaced pounds per square inch worldwide, though the United States still clings to psi. Weather maps usually quote it in hectopascals.
Q 18Albert Einstein's Nobel Prize in Physics was awarded specifically for his work on which phenomenon?
The photoelectric effect
Relativity was still considered too controversial by the Nobel committee. He was awarded the 1921 prize a year late, in 1922.
Q 19Marie Curie won the 1903 Nobel Prize in Physics and a second Nobel in 1911 in which field?
Chemistry
She remains the only person to win Nobel Prizes in two different sciences. The 1911 award was for discovering radium and polonium.
Q 20The Planck constant links a photon's energy to which property of the light?
Its frequency
That is why ultraviolet photons carry more punch than red ones. Since 2019 the constant has been fixed at exactly 6.62607015 × 10⁻³⁴ J·s.
His letter to Nature was titled 'Possible Existence of a Neutron' after only about two weeks of experiments. The discovery made it possible to create elements heavier than uranium.
Q 24In the acronym LASER, what does the letter S stand for?
Stimulated
The full phrase is light amplification by stimulated emission of radiation. Physicists have joked that LOSER, for light oscillation, would have been more accurate.
Q 25Superconductivity was discovered in 1911 in which metal, cooled to a few degrees above absolute zero?
Mercury
Heike Kamerlingh Onnes was studying resistance at cryogenic temperatures and watched it vanish completely. He won the 1913 Nobel Prize for his low-temperature work.
Q 26Léon Foucault's famous pendulum of 1851 was the first simple, direct demonstration of what?
The rotation of the Earth
He hung it first at the Paris Observatory and then under the dome of the Panthéon. A year later he did the same job with a gyroscope.
Q 27Which of the four fundamental interactions is by far the weakest at the atomic scale?
Gravity
A fridge magnet lifting a paperclip beats the pull of the entire planet. It only dominates at planetary scales because it is always attractive and reaches infinitely far.
Q 28Murray Gell-Mann took the word 'quark' from which novel?
Finnegans Wake
The phrase 'Three quarks for Muster Mark' appealed to him because he had proposed three of the particles. His co-proposer George Zweig preferred the name 'aces'.
Q 29How many flavours of quark are there in the Standard Model?
Six
They are up, down, charm, strange, top and bottom. Only up and down are found in ordinary matter; the rest appear briefly in accelerators and cosmic rays.
Q 30In which year did LIGO make the first direct detection of gravitational waves?
2015
The signal, GW150914, came from two merging black holes and was picked up on 14 September, but the announcement was held back until February 2016.