Flashlight - Wikipedia, the free encyclopedia

Description

A flashlight (also called a torch ) is a portable electric spotlight which emits light from a small incandescent lightbulb , or from one or more light-emitting diodes (LEDs). The light source is mounted in a housing which contains a parabolic reflector , a clear protective lens, a power source (typically electric batteries ), and an electric power switch .

While most flashlights are intended to be held in the hand, there are also helmet-mounted flashlights designed for miners and campers. Some types of flashlights can be powered by hand-cranked dynamos , electromagnetic induction or recharged by solar power.

The name flashlight is used mainly in the United States and Canada . In other English-speaking countries, the more common term is torch or electric torch .

History

In 1898, Joshua Lionel Cowen invented a decorative lighting fixture for potted plants which consisted of a metal tube housing a light bulb and a dry cell battery. It failed commercially, and so Cowen sold his company and patents to Conrad Hubert that same year and turned his attention to building and selling model trains. Hubert renamed Cowen's company the American Electrical Novelty & Manufacturing Company and, recognizing the true potential of Cowen's invention, hired David Misell to produce a tubular flashlight for portable use.

They donated some models to the New York City police, who responded favorably to it. These early flashlights ran on zinc-carbon batteries , which were poor at providing sustained currents; they would run down after a while and needed to rest before being usable again. Since these early flashlights also used energy-inefficient carbon filament bulbs, this happened rather quickly, and consequently they could only be used in brief flashes, hence the popular name flashlight .

General information

A typical flashlight consists of a small incandescent lightbulb (or, in recent models, an LED ) ...

Original URL

http://en.wikipedia.org/wiki/Flashlight

http://en.wikipedia.org/wiki/Flashlight