When you see a bright light then flames is it a physical change or chemical change explain how?

it is a chemical change because the substance is irreversible

mikias.a

(Alternative):

"Fire" itself is not a chemical change, it is merely incandescent gas. The visible flame is generated from multiple sources: black body radiation of fuel, ash and soot and also by photon emission due to de-excitation of gas molecules. These processes which create the light that we see as fire are not in themselves chemical changes.

Fire, however, needs energy in order to be created. These energy is usually produced by a chemical change, such as a redox reaction. It could also be produced by a nuclear change, such as fusion in the sun's core.

-Taedrin