Flashlight
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A flashlight (in American English) or torch (in Commonwealth countries) is a small, portable spotlight. Its function is a beam of light which helps to see. It usually requires batteries.
The light is made by a small light bulb. In the 20th century, it was usually an incandescent bulb. Nowadays most use LEDs, which work slightly differently. In 1896, the first dry cell battery was invented. Unlike previous batteries, it used a paste electrolyte instead of a liquid. This was the first battery suitable for portable electrical devices, as it did not spill or break easily and worked in any orientation. Sometimes the electricity comes from a small generator instead of a battery.
The torch can also refer to a flammable stick that is lit on fire to provide light and (or) heat.
Origin
Hundreds of years ago, people used candles or oil lamps for indoor light. Candles were expensive, and once the candle was gone, you would have to buy or make a new one or be stuck in the dark. When electricity was discovered and the light bulb was invented, David Misell, a British man working in Hubert's New York shop in 1898, came up with the idea of a light bulb that you could take with you, anywhere you wanted to go. Then, the torch was invented. The first flashlight has three D batteries which powered a small incandescent bulb. The bulbs would glow with a simple ON/OFF switch.[1]
Flashlight Media
A set of LED flashlights. C8 style on the left (Sofirn C8T: up to 1,310 lm), tube style on the right (Sofirn SP31; up to 1,100 lm).
The angle-head flashlight (Fulton MX-991U) on the left uses an incandescent bulb, while the adjustable angle-head flashlight (Streamlight Sidewinder) on the right uses LEDs to give white, red, blue, and infrared light
Miniature incandescent bulbs for use in flashlights: The tungsten filament bulb was essential to turn the flashlight from a novelty to a useful tool.
Two LED flashlight extremes: Olight SR90, 2,200 lumens (left), Foursevens Mini MLR2, 180 lumens (middle), AA battery for size comparison (right)
Miniature LED flashlight on a key chain, powered by lithium primary coin batteries
Multiple 5 mm LEDs may be used in small flashlights.
A medical halogen penlight to observe pupillary light reflex
An LED headlamp made by energizer. Runs on AAA batteries.
Nonincendive flashlight for use when inspecting areas full of flammable gas
A Metalsub cable diving torch
References
- ↑ "When Were Flashlights Invented?". 2020-08-31. Retrieved 2020-09-10.