Whoooooooooooooooooooosh! Bang! It can only be the sound of
Bonfire Night. But how do fireworks produce exciting displays like
this one?
Explosions:
Fireworks were first made in China over 1,000 years ago!
Gunpowder is what makes gunpowder explode. Potassium nitrate is the
most important part of gunpowder. This is what propels the firework
into the sky. A fuse is used to light the gunpowder, which ignites
to send the firework skyward. Once the firework is in the air, more
gunpowder inside it causes it to explode with a BANG!
Colour and sparkles:
Colours are made by burning metal salts. Did you know that if
you burn table salt (sodium chloride) it makes a yellow flame?
Burning different types of metal salts makes different coloured
flames. Have a look at this:
The bright sparkles in fireworks come from burning small bits of
metal, such as iron or steel filings.
Firework patterns:
A firework looks like this:
Picture from Anatomy of a
Firework, PBS
The fuse sets off a charge, which ignites the gunpowder. This
propels the firework into the sky.
Once the firework is in the sky, the gunpowder within the
firework ignites. This causes the 'stars', which contain metal
salts and iron filings, to explode in different colours and
sparkles. If the firework is in sections, the tars can be in
different compartments. These compartments explode at different
times, making different patterns.
The pattern of stars around the central gun powder charge
creates different patterns of fireworks. For example, if the stars
are in a circle around the black powder charge, you get a circle
display of colour. One mistake in the placing of the stars
and the whole pattern will be ruined!
Enjoy your fireworks - now you can explain to everyone how they
work.