Flashlight

LED Flashlights

USMC flashlights

Lightbulbs for flashlight

Sr90 qmini

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Keychain LED flashlight

Flashlight is a portable handheld light source powered by electricity. Typically, a flashlight consists of a light bulb or LED (Light Emitting Diode) housed in a reflective casing, a battery, and a switch. These components are encased in a protective shell, often made of plastic or metal, designed to be durable and sometimes waterproof or resistant to impacts.

History

The invention of the flashlight dates back to the late 19th century, following the development of the first practical incandescent light bulb by Thomas Edison and the dry cell battery. The early flashlights were rudimentary, consisting of a simple paper or fiber tube, a bulb, and a rough brass reflector. They were called "flash" lights because they could only provide light in short bursts due to the inefficiency of early batteries and bulbs.

Design and Function

Modern flashlights come in various designs, sizes, and functionalities, ranging from simple models for household use to specialized types for tactical, outdoor, and professional applications. The basic operation involves completing an electrical circuit that connects the battery to the light source, typically controlled by a push-button switch or a twist mechanism.

Light Sources

The evolution of light sources in flashlights has seen a significant transition from incandescent bulbs to LEDs. LEDs offer numerous advantages, including higher energy efficiency, longer lifespan, and greater durability. Some high-end flashlights incorporate multiple LEDs or advanced optics to provide adjustable focus or variable light output.

Power Sources

Flashlights are powered by various types of batteries, including disposable alkaline, lithium, and rechargeable batteries such as nickel-cadmium (NiCd), nickel-metal hydride (NiMH), and lithium-ion (Li-ion). The choice of battery affects the flashlight's weight, size, runtime, and brightness.

Features

Modern flashlights may include features such as adjustable brightness levels, strobe or SOS signals, zoomable focus, and programmable modes. Tactical flashlights, designed for law enforcement or military use, often have rugged construction, high brightness, and can be mounted on a weapon. Some flashlights are also designed for specific uses, such as diving, where they are built to withstand high pressure and water ingress.

Safety and Regulations

Flashlights, especially those designed for specific applications, may be subject to safety standards and regulations. For example, flashlights used in explosive environments must be certified as intrinsically safe, meaning they cannot ignite an explosive atmosphere under normal or fault conditions.

Cultural Impact

The flashlight has become an indispensable tool in daily life, used in a variety of settings from household to professional. It has also made significant appearances in popular culture, often symbolizing hope, discovery, and the human quest for knowledge in the darkness.

See Also

• Incandescent light bulb
• LED
• Battery
• Tactical flashlight
• Outdoor recreation