Light Sources
Lighting Fixtures > Light Sources
General Purpose Light Sources
A light source is what makes the light. In the home, the most common source of light is the incandescent light bulb. Halogen light, fluorescent light, and light-emitting diodes (LEDs) are three additional light sources that are commonly used in the home.
When a typical light bulb is used, it is called incandescent light.
Incandescent light happens when an electric current is passed through a
filament, which causes it to heat up and glow. The greatest
advantage to filament incandescent light bulbs is that they are cheap,
easy to find, and easy to replace. Incandescent lights also throw
a warm light. Incandescent light comes in many different watts and
is flattering, especially at low wattages. In addition, these types
of bulbs are available in many different shapes, sizes, and types.
They need no additional equipment and don't need to warm up before they
reach full illumination. Unfortunately, incandescent bulbs are not
as energy-efficient as certain other light sources.
Halogen lights use a different chemistry and process, which results in
the bulb not burning out when run at full voltage. The filament in
halogen bulbs burns at a higher temperature, so the bulbs are smaller and
made of quartz in order to stand up to the heat. Halogen light is
much whiter and cooler than incandescent light, and results in a crisp,
intense atmosphere. It's a great choice in rooms where you want to
intensify the definition of colors or create drama. Of all the
lighting technologies, halogen is the closest to daylight.
Fluorescent light is economical and energy-efficient, but it is not always
flattering to interiors or complexions. While the design and color
of fluorescent tubes and compact fluorescent lamps (CFLs) have improved
over the past few years, fluorescent lighting works best in workrooms and
showrooms where cool, bright, and diffuse light is required.
Unfortunately, fluorescent bulbs contain small amounts of mercury.
Light-emitting diodes (LEDs) are semiconductor devices that convert
electricity into directional light beams. LEDs last longer and are
more rugged and efficient than fluorescent, incandescent, or halogen light
sources. However, they are quite sensitive to excessive heat.
Special Purpose Light Sources
In addition to incandescent, fluorescent, and halogen, and LED lights, there are several other types of light sources. Most of these fall into a category called vapor discharge lamps, or simply discharge lamps.
Discharge lamps include metal halide, low-pressure and high-pressure
sodium, and high-pressure mercury lighting. You may not have heard
of these lamps because most are not used in household applications; their
use has primarily been reserved for commercial, public, and industrial
applications.
These alternative light sources are designed to be functional, and are rarely used to create atmosphere. They operate similarly to fluorescent bulbs, but differ in that they use different types of gas or metal vapor. They are both long-lasting and efficient sources of light.
Low-pressure sodium lights distort colors and work best as informational
lighting, whereas metal halide has excellent color rendering and is good
for backyard lighting. Discharge lamps usually have large bulbs that
can take several minutes to warm up. They require control gear and
must be disposed of carefully due to the toxic material inside.
Neon, another type of lamp that produces low-level colored lighting, is
primarily used for decorations. Also called cold cathode, neon is
most often seen in commercial signs. Neon lighting is expensive, and it
operates at a very high voltage. It's rarely used in homes, although
sometimes it can be put behind moldings to produce interesting
architectural effects.
Fiber optics is a more modern type of lighting in which light is shone down thin strands of coated fiberglass or acrylic. The light emerges only at the end, which means that optic lighting is cool at the point of delivery. Fiber optics lighting is mostly used for novelty effect.
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