What is a key characteristic of the foam created by a foam extinguisher?

The foam created by a foam extinguisher is characterized as being light and capable of expansion. This expansion is crucial because it allows the foam to spread and cover a larger surface area, forming a blanket over the flammable liquid or fire. The lightness of the foam is also essential for effective application; it helps in creating a barrier that smothers the fire, preventing oxygen from reaching the flames.

Additionally, this property contributes to the foam's ability to cling to surfaces, which aids in extinguishing the fire and preventing re-ignition. The expansion of the foam enhances its effectiveness by allowing it to fill gaps and spaces, providing complete coverage over the fire source.