How does a smoke detector sense smoke?
The Electric Messenger
How does a smoke detector sense smoke?
You're asleep. The kitchen is quiet. Then — a shrill beep pierces the air. The smoke detector on the ceiling has sensed danger before you even smelled it. How does a little plastic disc know there's smoke in the room?
Inside that disc sits a tiny chamber no bigger than a thimble. Air flows through it constantly, in and out, sampling the room. Most of the time, the air is clear — just oxygen and nitrogen molecules tumbling through. The detector doesn't care about those.
