A Wonderleaf question
How does a smoke detector sense smoke?
a real page from the book
A smoke detector senses smoke by noticing when tiny particles in the air disturb an electrical signal inside it. In one common type, americium-241 helps make charged bits in a small chamber. Clean air lets a steady current pass; smoky air interrupts it, so the alarm sounds.
That is why the device can react before a person smells anything. Smoke bits are much larger than ordinary air molecules, so they get in the way fast. A small change in a hidden circuit becomes a loud warning from the ceiling, giving everyone time to move.
Wonder words
- smoke
- current
- ions
- alarm
Try it out
Check one smoke alarm together tonight, then decide where every person would walk if it sounded during dinner.
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