Fire is the chemical reaction of a fuel and oxygen to produce carbon dioxide, water vapor and heat. It is a self-sustaining chain reaction that can continue as long as fuel and oxygen are available.
Fire Science is a branch of physical science that deals with the study of fire behavior, combustion, and flame evolution. Its applications include fire investigation, wildfire management, and fire protection.
The most obvious properties of fire are its visible light and radiant energy. It is also very hot and may produce a loud sound when it expands quickly. Some materials, such as metals and plastics, are able to burn but do not release much light or heat. They can be extinguished with water or other non-flammable liquids and chemicals.
Most people are familiar with the concept of burning wood, but not all know that any type of combustible material can burn, even water. The first step in a fire is to create heat, which can be done with a match, a flashlight or another source of concentrated heat. The heat causes the atoms in the fuel to vibrate until they break free of the bonds holding them together and are released as volatile gases. The released atoms then react with the oxygen in the air to form the chemical reaction of combustion. This chemical reaction releases a lot of heat, which is why it generates flames and intense heat.
The heat generated by the fire keeps the remaining fuel at its ignition temperature and the reactions that produce it can keep generating more heat. This is how a fire can sustain itself as it spreads through a building or forest. If enough of the fuel is consumed or the rate of the reaction slows down, the fire will stop releasing heat and eventually turn into ash.
There are three essential elements that are needed for fire to exist: a flammable or combustible fuel in combination with oxygen gas or another oxygen-rich substance (called an oxidizer) and sufficient heat. This is called the Fire Triangle. Without one of these, fire cannot start or continue.
During the process of a fire, heat energy is transferred from hot vaporized fuel to nearby objects by conduction and radiation, as well as by convection. The result is a wave of heat that moves through the air and can cause the walls of a room to feel warm, or even hot. The radiated heat can also be used to control the flames, by placing a piece of cloth over the flames and letting it absorb the heat until it dries out.
Incomplete combustion of the fuel gas can result in black soot, and incomplete combustion of organic molecules produces a flame with a blue color that comes from the emission of single-wavelength electromagnetic radiation. Both of these features give a fire its characteristic glow. The chemical composition of a flame depends on the fuel and the oxidizer used in it, but typically contains carbon dioxide, water vapor, hydrogen, nitrogen and oxygen.