What do you know about fireworks? – answers and explanations
Here are the answers to all 15 questions in the What do you know about fireworks? quiz, each with a short explanation. Bangs, sparks and colours — how fireworks really work. Haven't played yet? Take the quiz first and compare your score.
Play the quiz · 15 questions1. When did alchemists in China first record gunpowder?
Answer: During the Tang dynasty (9th century)
Gunpowder emerged from Tang dynasty (618-907) Daoist alchemy, with the first confirmed formula in the text Taishang Shengzu Jindan Mijue of 808 AD; the alchemists were chasing an elixir of immortality, not a weapon.
2. Which US holiday is famous for big fireworks displays across the country?
Answer: Independence Day
Fireworks have marked the Fourth of July since 1777, the first anniversary of independence, when Philadelphia celebrated with a fireworks display.
3. Why do you see a distant firework burst before you hear its bang?
Answer: Light travels faster than sound
Light arrives almost instantly, while sound travels at about 343 metres per second, so a burst 1 km away is heard roughly three seconds after it is seen.
4. Saltpetre, a key gunpowder ingredient, is known to chemists by what name?
Answer: Potassium nitrate
Saltpetre is potassium nitrate (KNO3), the oxidiser that supplies oxygen to burn the charcoal and sulphur in black powder, typically making up about three quarters of the mixture.
5. Japan's spectacular summer firework festivals are known by which word?
Answer: Hanabi
Hanabi (花火, literally fire flowers) is the Japanese word for fireworks, and big summer displays are called hanabi taikai; the tradition traces to a 1733 display on Tokyo's Sumida River after famine and disease.
6. Which metal's salts give fireworks their brilliant deep red colour?
Answer: Strontium
Strontium salts such as strontium carbonate and strontium nitrate emit light around 650-700 nanometres, giving fireworks their deep red. Barium gives green, copper blue and sodium yellow, and mixing strontium with copper yields purple.
7. Bastille Day fireworks in Paris light up the sky around which landmark?
Answer: The Eiffel Tower
On 14 July, France's national day, Paris stages a large fireworks show launched from the Eiffel Tower and the Trocadéro area.
8. The spinning Catherine wheel firework recalls a saint martyred in what way?
Answer: Broken on a spiked wheel
The spinning Catherine wheel is named after Saint Catherine of Alexandria, who by tradition was condemned around AD 305 to die on a spiked breaking wheel; legend says it shattered at her touch, so she was beheaded instead.
9. Which city's New Year fireworks erupt from its Harbour Bridge and Opera House?
Answer: Sydney
Sydney's New Year's Eve display is fired from the Harbour Bridge and barges around the Opera House, drawing about a million spectators to the harbour foreshore. Auckland uses its Sky Tower and Rio centres its show on Copacabana beach.
10. What actually makes a firework's loud bang?
Answer: A shock wave from rapidly expanding gases
The bang comes from combustion gases expanding faster than the speed of sound, compressing the surrounding air into a high-pressure shock wave heard as a boom. Tightly packed flash powder in salutes makes the sharpest reports.
11. Which hand-held firework do people wave around to draw shapes in the air?
Answer: A sparkler
A sparkler is a metal wire coated in a slow-burning mixture that throws off bright sparks; despite its gentle look, its tip burns at over 1,000 °C.
12. In gunpowder, what is saltpetre's main job?
Answer: Supplying oxygen so the fuel burns fast
Saltpetre (potassium nitrate) is the oxidiser in black powder, releasing oxygen so the charcoal fuel and sulphur burn extremely rapidly without needing air. The classic mixture is roughly 75% saltpetre, 15% charcoal and 10% sulphur.
13. Before gunpowder, Chinese festivals made bangs by roasting which plant?
Answer: Bamboo
Long before gunpowder, Chinese people threw green bamboo stems into fires; trapped air in the hollow segments expanded until the stalk burst with a bang, believed to scare off evil spirits. The Chinese word for firecracker, baozhu, still means "exploding bamboo".
14. Guy Fawkes Night fireworks light up British skies on which date?
Answer: 5 November
Bonfire Night is held every 5 November, marking the failure of the 1605 Gunpowder Plot in which Guy Fawkes was caught guarding explosives beneath the House of Lords.
15. Which law of motion explains how a firework rocket pushes itself skyward?
Answer: Newton's third law of motion
A rocket works by Newton's third law: hot gas blasted backwards out of the nozzle produces an equal and opposite forward thrust, so no air to push against is needed.