Flashlights

Flashlights

Flashlights, also known as torches in some countries, are portable hand-held electric lights. The source of the light is usually an incandescent light bulb (lamp) or light-emitting diode (LED). A typical flashlight consists of a light source mounted in a reflector, a transparent cover (sometimes combined with a lens) to protect the light source and reflector, a battery, and a switch. These are housed in a case designed to fit in the hand.

History

The invention of the dry cell and miniature incandescent electric lamps made the first battery-powered flashlights possible around 1899. Today, flashlights use mostly LEDs and run on disposable or rechargeable batteries. Some are powered by the user turning a crank or shaking the lamp, and some are powered by solar panels.

Types

Flashlights come in a wide variety of sizes, from small keychain-sized models that can run on button cells to large hand-held units that can use long-life rechargeable batteries. Special types include:

• Headlamps, worn on the head to allow the user hands-free operation
• Tactical flashlights, designed for military or police use, often capable of producing a very high level of brightness
• Dive lights, designed for underwater use, with high water resistance and pressure resistance
• Shake flashlights, which generate power by shaking, no batteries required
• Solar-powered flashlights, which use solar cells to recharge their batteries

Technology

Early flashlights ran on zinc-carbon batteries, which could not provide a steady electric current and required periodic "rest" to continue functioning. Modern flashlights have more sophisticated electrical systems and use batteries such as alkaline batteries, lithium batteries, or rechargeable NiMH, NiCad batteries. The light source has evolved from incandescent bulbs to energy-efficient LEDs that produce more light per watt of electricity.

Usage

Flashlights are used in various situations where portable light is needed — for example, in emergencies when power outages occur, in camping, hiking, and other outdoor activities, by military and law enforcement, in industrial and construction settings, and by anyone needing to navigate in the dark.

Safety and Regulations

In some jurisdictions, flashlights must meet specific standards for brightness, water resistance, and impact resistance. For example, the ANSI/NEMA FL 1 standard provides a consistent method for comparing basic flashlight performance.

Environmental Impact

The shift to LED technology has significantly reduced the environmental impact of flashlights by increasing battery life and reducing waste. Rechargeable flashlights further decrease the need for disposable batteries, lessening the environmental footprint.

See Also

• Lantern
• Emergency lighting
• Searchlight