If you think about the loudest, most annoying sound in the world, it’s probably a smoke alarm.
It has to be loud though to grab your attention and save peoples’ lives!
But how do they work?
Smoke is made up of tiny particles – that’s just another word for “bits”. And that’s the reason why smoke can leave a smell on clothes or make you cough if you breathe it in, because the particles get stuck on things.
Some smoke alarms have tiny lights inside and if the smoke particles get in the way of the lights, the alarm is activated.
A different type of alarm uses chemicals which give out an electrical charge. Smoke particles inside the detector change the amount and type of electrical charge – and this sets off the alarm.
Watch some more facts about smoke alarms…