A flashlight or torch is a hand-held portable
electric spotlight. It is known as a flashlight mainly in
the United States and as a torch in most Commonwealth countries.
A typical flashlight consists of a small
electric lightbulb with associated parabolic reflector, powered
by electric batteries, and with an electric power switch.
The components are mounted in a housing that contains the
necessary electric circuit and provides ease of handling,
a means of access to the batteries for replacement, and a
clear covering over the lightbulb for its protection.
Although a relatively simple device, its
invention did not occur until the late 19th century because
it depended upon the earlier invention of the electric battery
and electric light. The batteries in the first ones were of
such short useful life that the common method of operating
them was to flash them just long enough to discern the environs,
and only as needed; hence the term "flash-light". |
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Recently, flashlights which use light-emitting
diodes (LEDs) instead of conventional lightbulbs have become
available. LEDs are far more efficient, and use less power,
than normal lightbulbs, and so torches which use them have
longer battery lifetimes. LEDs also survive sharp blows that
often burn out conventional lightbulb models. Another innovation
in flashlight design is the headlamp, a flashlight worn on
the head for hands-free operation. Powerful headlamps mounted
on helmets have been used in mining for decades, but general-purpose
ones with fabric straps are now also available.
Most flashlights are cylindrical in design,
with the lamp assembly attached to one end. However, early
designs came in a variety of shapes. Many resembled lanterns
of the day, consisting largely of a box with a handle and
the lamp attached to the front. Some others were made to have
a similar appearance to candles. It is possible that future
developments of battery and LED technology will bring interesting
new designs. For instance, one very small light that exists
now in 2004 consists of a few LEDs with a switch, designed
to be an endcap for a 9-volt battery.
Small LED torchHigh-quality flashlights go for as much as
several hundreds of dollars. Such flashlights are very advanced,
using special batteries, have adjustable brightness levels,
dive-depth waterproof ratings, interchangeable optics, and
are very bright.
Most common Torches and Flashlights run from standard size cells such as AAA, AA, C and D. Depending on how you use the torch will have an effect on which type of chemistry cell is best for you to use in the torch.
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