There are two different smoke detectors that may be installed in your house; The two types are photoelectric and ionization. Below is an explanation of how the ionization type detectors work.

Smoke detectors should be checked regularly, the battery should be replaced twice a year and the entire unit should be replaced every ten years.

An ionization type smoke detector relies on a small amount of radioactive material to aid in the detection of smoke.

This radioactive material is located at the bottom of the ionization chamber. The ionization chamber contains two metal plates, one with a positive charge and one with a negative charge.

Alpha particles, emitted by the radioactive source, enter the ionization chamber through a small hole in one plate and cause Oxygen and Nitrogen atoms to be either positively or negatively charged.

These atoms then travel to the opposing plate. This flow of atoms or electrons registers as a small but constant flow of electricity.

When smoke enters the ionization chamber, it disrupts the flow of electrons and stops the flow of electricity.

Once the flow of electricity stops, the siren will go off.