A Surefire U2 flashlight

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

An 1899 Eveready flashlight, one of the earliest flashlight models. 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 high power torchA typical flashlight consists of a small incandescent lightbulb (or, in recent models, an LED) 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 incandescent light bulb.

Incandescent

Incandescent flashlights use bulbs that contain a heated-up coil of tungsten wire, which gives off light energy as well as heat. The bulbs are filled with gas (usually argon, perhaps with a trace of a halogen: in higher quality models, xenon is used). A popular example of an incandescent flashlight is the Maglite by Mag Instrument and are capable of producing 40 to 50 lumens 1.