REYANNA LAMBIE
Flashlights
Flashlights and Mirrors
The optics process occurring in a flashlight is called REFLECTION.
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Concave mirrors are used with a reflector.
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The lamp is located at the focal point of the reflector -creating parallel beams of light leaving the surface of the mirror. This is the form of light the eye sees leaving the flashlight.
Diagram* When the incident ray passes through the focal point the light reflects parallel.
Light Source vs Flashlight Design:
The most standard flashlights operate on three individual incandescent light bulbs. Incandescent bulbs emit light when a coil filament inside the bulb is heated when it resists the exposure to an electrical current.
Camping lanterns use fluorescent bulbs and are powered by heavy duty batteries. Fluorescent bulbs are more efficient however, their beam of light is weaker. These bulbs emit light when an electrical current passes through the bulb which ‘excites’ the gas molecules producing an ultraviolet light which makes the powder coated inside the bulb glow.
Flashlights used for industrial and professional purposes are specially designed, made from heavier and more durable materials because they need to produce brighter light. Brighter beamed flashlights are typically used by police, firefighters and the military.
Novelty flashlights are designed for children, made from light plastic and have an appealing visual design. The designs consist of popular tv show characters and music artists.
There are also specialty lights designed for specific purposes. Snake lights can bend so that light is provided in hard to reach places.
Battery life is an important factor to consider when designing specialty flashlights. Some flashlights are rechargeable others use low energy consumption lights like LEDs.
Modern flashlights use LED light bulbs because they last longer although they are not as bright as the incandescent bulbs. LED bulbs emit light when exposed to low levels of electricity. These bulbs when used in flashlights are often placed in front of an aluminum reflector which is used to control the angle of the beam of light so that light will emit parallel.