A flashlight is commonly called a torch. It is a portable electric spotlight, held by the hand. In the United States and Canada, it is known as a flashlight.
In the Commonwealth countries, it is known as a torch. A flashlight consists of a small electric light bulb with associated parabolic reflector. It is powered by electric batteries and has an electric power switch. The flash bulb comprises of a covering over the light bulb for protection and means of access to the batteries for replacement.
It was invented in the late 19th century and its invention depended upon the earlier discovery of electric battery and incandescent light bulb. Flashlight gets its name from the batteries used in earlier times that operated long enough to discern the environment. Due to their short useful life, the flashlights were used to flash for a small duration of time allowing the person to just discern the environment. Hence the term "flash-light". The light-emitting diodes (LED) flashlights are now used instead of the conventional ones.
The Lumileds Corporation of San Jose, CA introduced the Luxeon LED in 1999. With a high-power white-light emitter, it made the LED flashlights more powerful wit a better running time. Arc LS was the first Luxeon LED flashlight made in the year 2001. The powerful LED lights generate significant amount of heat. In an incandescent light, a significant fraction of heat generated is radiated into the beam itself which you can feel by going near the powerful incandescent flashlight. A LED flashlight radiates little heat into the beam.
The Heat is removed by conducting and transferring it to the flashlight body. The high-powered LED flashlights have metal bodies, which can conduct the heat generated. As a result, they are warm when in use. Headlamp is another type of flashlight design. Since a flashlight needs to be carried by the hand, headlamps have come up to aid hands-free movement.
They are placed on helmets and have been used in mining for many years. Almost all the flashlights are cylindrical in design with a lamp attached to one end. You can get the high-quality flashlights by spending several hundreds of dollars. They are highly advanced using special batteries, and have adjustable brightness levels, dive-depth waterproof ratings and interchangeable optics. Self-powered flashlights are available. Some torches use solar panels to recharge their batteries during the day.
A spring and a winding handle powers the clockwork torch for a period of time. Certain flashlights have an electrical generator built into it.
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