Physics Question #480

paul valent, a 38 year old n/a from quakertown asks on December 20, 2001,

Is the line spectrum that is produced by a fluorescent tube the result of some of the visible light produced by the excitation of the mercury passing through the phosphor or is it from the white light produced by the phosphor?

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The answer

Barry Shell answered on December 21, 2001

Yes. While they are not line spectra, here are some spectra of daylight, incandescent and fluorescent light compared. You can see big spikes in the ultraviolet for the fluorescent bulb spectrum. From my reading on the web, I don't think the mercury discharge creates very much visible light, however. Most of the visible light comes from the phosphor coating inside the bulb.

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