How is the light produced when an object is burnt?

 A chemical reaction is a simple rearrangement of atoms leading to formation of newer substances(products). Hence, to favor the rearrangement,breaking of bonds in the reactants and making of bonds between atoms in the products occur. Due to this in every chemical reaction there is involvement of energy (liberation or absorption depending on the bond energies of the elements in the reactant and the products). The energy involved may be light, heat or electrical energy. All combustion (burning) are chemical reactions of a fuel with oxygen in which carbon-hydrogen and oxygen-oxygen bonds are broken in the reactants (except hydrogen) and carbon-oxygen and hydrogen-oxygen bonds are formed in the formation of the products.

The bond energies of these atoms are in such a way that the energy liberated is always more than the energy consumed for the breaking of bonds. The net energy is liberated in the form of both light and heat.

 Courtesy : The Hindu