5 key features of Infrared

1) used by electrical heaters, cookers for cooking food, and by infrared cameras which detect people in the dark 2) has frequencies which are absorbed by some chemical bonds 3) The internal energy of the bonds increases when they absorb infrared light, which causes heating 4) All objects emit infrared light 5) Can be detected by infrared cameras. This 'thermal imaging' is useful for detecting people in the dark