Talk:Mercury-vapor lamp
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[edit] Spectrum on page not representative of mercury vapor lamp
- Whoever added the visible spectrum to the right of the page, please consider replacing it with a (high pressure) mercury vapor spectrum. The spectrum added is that of a triphoshor fluorescent and that is a LOW pressure mercury vapor lamp. Not typical of mercury vapor lamps, which are high pressure.
The article states that:
For placements where light pollution is of prime importance (Eg. An observatory parking lot), low pressure sodium is preferred. As it emits light on only one wavelength, it is the easiest to filter out.
low pressure sodium lamps don't emit light of only one wavelength. I can still see red and blue colors in low pressure sodium lamp light. --Abdull 16:39, 30 Mar 2005 (UTC)
- I think you're confusing low-pressure sodium with high-pressure sodium. The light from LPS lamps is, essentially, monochromatic. (It's really two very-closely-spaced wavelengths, but for most practical purposes it's "monochromatic".) The LPS lamp fixtures hold long tubes that look like fluorescent lamps without any phosphor.
- High-pressure sodium lamps, though, while still distinctly yellowish or orangy, are definitely NOT monochromatic. They still have a strong sodium line, but the very high pressure broadens it. Because the filling is actually sodium amalgam, they also have prominent mercury lines and usually neon as well. The HPS sodium lamp fixtures look just like mercury-vapor lamp fixtures.
- It's rather bizarre to stand in an area illuminated solely by LPS sodium light; there really is no color (other than orange) to be perceived. In the USA, you don't find too many pure-LPS sodium light installations, but one is the tunnel on the Wilbur Cross Parkway in Connecticut. You can also find it at the entries to The Big Dig here in Boston, Massachusetts, but it's combined with other lighting so the monochromatic effect is lost.
- Atlant 16:50, 30 Mar 2005 (UTC)
[edit] Ultraviolet is your friend!
The article could use a discussion of the uses of UV generated by Hg lamps, for example in photolithography, microscopy and last but not least, tanning salons! Alison Chaiken 02:03, 3 February 2006 (UTC)
- Alison, this is Wikipedia, so you know what to do: be bold!
- Atlant 13:55, 3 February 2006 (UTC)
[edit] How is that
It is written that "The mercury vapor lamp is a negative resistance device and requires auxiliary components (for example, a ballast) to prevent it from taking excessive current". Why does it takes 'excessive current' in the negative resistance regeion. —The preceding unsigned comment was added by 59.94.115.159 (talk • contribs) .
- Have you read the article about negative resistance? But in brief:
- For an ordinary resistance, the resistance of the device doesn't change so current flow through the resistance only rises in proportion to the voltage across the device. If the voltage is limited, so will the current flow be limited.
- For a negative resistance device, though, as more current flows through the device, its resistance decreases. If connected to a fixed voltage source, this reduced resistance allows more current to flow which further reduces the device's resistance which allows more current to flow until... POOF!
- In gas discharge lamps like the mercury vapor lamp, the negative resistance occurs because, as more current flows, there are more current-conducting ions formed in the gas column, decreasing the resistance...
- Atlant 15:44, 9 October 2006 (UTC)
[edit] Picture?
This page needs a picture to show people what these lamps usually look like, and what their color is. If anyone could get that, it would be great. I will also try to get a picture. E.boyer7 22:57, 2 January 2007 (UTC)
