Flashlight
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 the United Kingdom and most British 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".
Recently, flashlights which use LEDs instead of conventional lightbulbs have become available. LEDs are far more efficient than, and use less power than normal lightbulbs, and so torches which use them have longer battery lifetimes. 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.
You might think of a flashlight as a $20 item at maximum, but actually 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.
See also: Maglite.
External link
Hobbyists who enjoy modifying and collecting flashlights enjoy a forum at Candlepower Forums. Candlepower forums, also known as CPF, is basically the best informational flashlight site on the net.