I’ve always had the wrong idea of how smoke detectors worked.

Smoke detectors have two electrically charged plates and a radioactive source. The radioactive source ionizes the air, making current flow.

When smoke penetrates the device, the attenuation disrupts the current flow, firing the alarm.

But one detail was missing: how exactly the smoke disrupts that flow??

I assumed it was because the smoke inserted caused attenuation. But today I learned that the smoke particles attach themselves to the charged ions, which hinders their movement and decreases the current, which in turn triggers the alarm.