• Question: How is light produced when a object burns ?

    Asked by reaganbrien to Ben, Dave, Ed, Sam, Susana on 24 Jun 2013.
    • Photo: David Briggs

      David Briggs answered on 24 Jun 2013:

      When something burns, the energy that is released by burning is released as electromagnetic radiation – most of this is released as infra-red radiation (heat) but some of it is emitted in the visible part of the electromagnetic spectrum.

      The actual photons of light emitted are caused by a process called atomic excitation – the large amount of energy in the flame excites electrons in atoms and they are ‘promoted’ to a higher energy shell/orbit around the nucleus – but this is unstable, and so the electron released the extra energy as a photon and the electron falls back to its normal orbit/shell.

      The wavelength of the photon depends on what is being burnt.

    • Photo: Benjamin Hall

      Benjamin Hall answered on 24 Jun 2013:

      As Dave has stated, the heat in the chemical reaction ‘excites’ electrons to higher energy levels. When the electron drops back down the energy is released and has a characteristic wavelength based on the type of atom being burned. This wavelength gives rise to the light we see and the colour differs depending on the wavelength.

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