• Question: The light coming from a coloured light bulb is (mostly) white and therefore requires a coloured glass bulb filter to show any colour. Can coloured light come from a transparent glass bulb? Also, what wavelengths of light do light bulbs emit? Is it 'coincidentally' just the RGB waves that are needed to make white light perhaps?

    Asked by conn207 to Antonia, Douglas, Hugh, Matt, Tom on 15 Jun 2010 in Categories: .
    • Photo: Antonia Hamilton

      Antonia Hamilton answered on 14 Jun 2010:

      Different light bulbs emit different wavelengths. Old fashioned filament bulbs emit light across all wavelengths, so then you need coloured glass to make a particular colour. Compact fluorescent bulbs emit just a few wavelengths, so you can get specific colours more easily. Think of the neon signs which spell out words in shop windows which are made of bent light bulbs.

    • Photo: Matthew Hurley

      Matthew Hurley answered on 14 Jun 2010:

      Yes – it depends what the filament is made of. Different filaments produce different colours. I presume lightbulbs produce light in the wavelengths of visible light (as well as probable some unseen wavelengths).

    • Photo: Hugh Roderick

      Hugh Roderick answered on 15 Jun 2010:

      I don’t know

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