Question: How is the light produced when an object is burnt?

Ceri Brenner answered on 14 Jun 2011:

When something is burnt, the atoms are heated to a high temperature and the electrons in the atoms are excited to higher levels than their ground (rest) state. It’s like saying the atoms are excited with all the energy. In order to get to their normal state, they get rid of their energy in the form of radiation. Light is just radiation that we can see. Another way to think about it is if something is hot, then it naturally wants to cool down. To cool down means to give off the heat energy to the surrounding air. The heat energy is given off in the form of an electromagnetic wave. The colour that we see in a bunsen burner for example, is to do with the temperature of the flame (in this case the air is being burnt). The coolest flames are yellow-ish and as the temperature increases, the type of radiation that is given off moves towards the blue end of the electromagnetic spectrum of visible light. Really really hot temperature flames would give off UV light (but we can’t see it cos it’s invisible to us) and that’s also why the sun gives off UV rays.