Fluorescent Lighting

    
Although there are a large number of lighting options, the majority of lighting in homes is done by either incandescent or fluorescent lights. Fluorescent lighting has a considerable advantage in energy efficiency over incandescent lighting. Fluorescent lights can produce 50-100 lumens/watt compared to about 15 lumens/watt for incandescent bulbs.


The familiar geometry of fluorescent lights involve a long narrow glass tube with two electrical connections on each of the metal caps which seal the ends of the tube. The tube is filled with noble gases such as argon, neon or krypton to suppress chemical reactions resulting from the electrical discharges in the tube. According to Bloomfield, these gases are at a pressure of about 0.3% of atmospheric pressure. A few drops of mercury is placed in the tube, and the vapor pressure is sufficient to constitute something like one in a thousand of the atoms inside the tube.

If electrons are removed from the mercury atoms by collisions with high speed electrons, they can produce light by emission (see mercury spectrum) when electrons make transitions downward to fill the electron gaps produced. One key to getting light out of the fluorescent tube is then to produce the high speed electrons which can "excite" the mercury atoms so that they will produce light. This is done in most fluorescent tubes by heating a filament in the end of the tube, which frees some electrons . Other types use high voltages to eject electrons from electrodes at the ends. Once freed, the electrons can be accelerated in the tube by the applied AC voltage. Some of the electrons transfer energy to the mercury atoms in collisions, so that one or more of the electrons of the mercury atom is elevated to an excited state. Once the electrical discharge in the tube is started, the current must be controlled to maintain a steady light source. This is done by coil arrangement called a fluorescent light ballast.

The process of producing light from the mercury atoms is fairly efficient, but a large part of it is in the ultraviolet rather than the visible range. The final transition of the electrons to the ground state of the mercury atom produces light at 254 nm, considerably below the blue limit of human vision at about 400 nm. The ultraviolet light does not get through the glass envelope of the tube, but because of its high quantum energy it can be used to advantage in producing visible light. To produce light in the visible range, the inside of the tube is coated with a phosphor powder. When the ultraviolet light strikes the powder, it produces excitations of the electrons of the phosphor which then produce visible light by a process called fluorescence. Ultraviolet photons associated with the 254 nm uv light have quantum energies of 4.9 electron volts, whereas the energy range for the visible photons which we can see is from 1.6 to 3.1 eV. Since there are many intermediate levels for the electrons to drop to after being excited by the uv photons, they can produce visible photons of light throughout the visible range, producing nearly white light.

The production of white light is a challenging undertaking. In the case of the fluorescent lights, a carefully selected and blended set of phosphors is used so that the wavelengths at which it fluoresces are distributed evenly over the visible range. Current fluorescent lighting uses six standard phosphor blends: cool white, deluxe cool white, warm white, deluxe warm white, white, and daylight. The daylight phosphor which was used in early fluorescent lights tips the light toward the blue end and is criticized as being "cold". The "cool" phosphors resemble daylight and are more nearly color neutral, while the "warm" phospors tip the spectrum toward the red end and resemble incandescent lighting. http://danceshoes.hyperphp.com/ http://bariatric.atwebpages.com/Car%20alarms
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I build a MH hood

starting from a kit (ballast, socket, bulb, aluminum
sheet) which has been running a couple of months quite happily. The bulb
is about 3.5" in diameter and 8" long, but the socket is another 1.5" or
so. I originally was going to use a small fan, but it's too noisy for my
living room. The hood itself is mahogony which obviously can't take the
heat of the lamp (they get HOT). My solution was to line the interior
of the hood with aluminum sheet, both the polished sheet from the kit and
somewhat dull aluminum flashing from a hardware store. I spaced it about
1/4" off the wood using metal spacers and screws, leaving a complete air
gap all the way around. I left two holes 2"x3" in the back top, and a
3/4"x12" slot at the front bottom to get convectional cooling across the
bulb. This all seems fine, the exterior of the wood (3/8" thick) is warm to
the touch, not at all hot.

The Coralife bulb I got has a glass envelope that sheilds UV, however I
didn't like the idea of a very hot piece of glass 8" above sea water, so I
covered the bottom except for the cooling slot with 1/4" plexi, also spaced
1/4" down so there's an air opening around the bottom. The plexi overlaps the
sides, so there's no direct path for a splash to hit the bulb. I haven't
blown up any yet :^)

If you build such a system be sure to stick around for several hours
when you first use it, these bulbs really are hot. I could easily
imagine them causing a fire if the cooling and/or insulation weren't
adequate, burning down your house would ruin your whole day. Perhaps
people should make sure that even if one fan went out in a hood that
the resulting heat wouldn't be excessive. http://danceshoes.hyperphp.com/ http://bariatric.atwebpages.com/Alarm Car System Vehicle
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home lighting

Lighting and lighting in homes can make a huge difference in how you and others feel about your home. Lighting adds drama and aesthetics to a room. Done the right way, it can make a small room look airy and open and a large room seem cozy and attractive. It can create a motivating incandescent bulbs atmosphere for an entertaining evening, or a feeling of relaxation after an exhausting day at work. Lighting can make a difference in several ways. There are three fundamental types of light by emission for a home -- general, task and accent. A high-quality lighting plan amalgamates these types to light an area according to style and function. In the bathroom, it is best to have a shadow-free ultraviolet light, even lighting that facilitates easy grooming, shaving and applying makeup. For bedroom lighting, you want to produce a general atmosphere of quiet recreation soft lighting, yet offer some bright spots for activities like reading. The dining room lighting should be practical and aesthetically attractive special lighting. This lighting sets the mood for an array of functions. The kitchen is first and foremost a working area, but it is also a place for family and friends to gather. Lighting that is relaxed and purposeful is required for example fluorescent lighting. Living rooms need general lighting for entertaining and viewing television, task fluorescent lighting for sewing or reading and accent lighting for plants, artwork and appealing architectural features. Dimming controls are perfect for living rooms, as they allow one to design lighting to go with each mood and activity. Outdoor lighting and solar lightingaugments the splendor of your property, makes the home safer and increases the number of enjoyable hours you spend outside the house. Alarm Kiddie Smoke
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I build a MH hood

starting from a kit (ballast, socket, bulb, aluminum
sheet) which has been running a couple of months quite happily. The bulb
is about 3.5" in diameter and 8" long, but the socket is another 1.5" or
so. I originally was going to use a small fan, but it's too noisy for my
living room. The hood itself is mahogony which obviously can't take the
heat of the lamp (they get HOT). My solution was to line the interior
of the hood with aluminum sheet, both the polished sheet from the kit and
somewhat dull aluminum flashing from a hardware store. I spaced it about
1/4" off the wood using metal spacers and screws, leaving a complete air
gap all the way around. I left two holes 2"x3" in the back top, and a
3/4"x12" slot at the front bottom to get convectional cooling across the
bulb. This all seems fine, the exterior of the wood (3/8" thick) is warm to
the touch, not at all hot.

The Coralife bulb I got has a glass envelope that sheilds UV, however I
didn't like the idea of a very hot piece of glass 8" above sea water, so I
covered the bottom except for the cooling slot with 1/4" plexi, also spaced
1/4" down so there's an air opening around the bottom. The plexi overlaps the
sides, so there's no direct path for a splash to hit the bulb. I haven't
blown up any yet :^)

If you build such a system be sure to stick around for several hours
when you first use it, these bulbs really are hot. I could easily
imagine them causing a fire if the cooling and/or insulation weren't
adequate, burning down your house would ruin your whole day. Perhaps
people should make sure that even if one fan went out in a hood that
the resulting heat wouldn't be excessive. http://danceshoes.hyperphp.com/ http://bariatric.atwebpages.com/Fire%20alarms
Alarm Car System Vehicle
Smoke Water Alarms
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