Advantages of LED Flashlight using LEDs over conventional light bulbs
Most flashlights now are fitted with LEDs instead of the traditional incandescent light bulbs. It is only a matter of time these filament light bulbs are entirely replaced by light emitting diodes (LED) as the preferred choice of lighting source.
LED's are used in most consumer devices such as flashlights, handphones, laptops, watches and toys.
The fact that LEDs are encased in plastic materials
instead of glass make them lighter and more durable.
LEDs are favored over light bulbs because they produce negligible heat and
requires very little energy for power. This afforded mini-sized devices to
be developed that needs only one battery as its power source.
A Little About Incandescent Light Bulbs
The incandescent light bulb is one of three types of lighting devices, the other two being the fluorescent and high-intensity discharge. They differ in terms of their construction, shape, size, electricity consumption (wattage), color and the required pressure of electricity (voltage).
The incandescent light bulb is commonly used in a variety of household devices. It usually comes in a sealed glass bulb with a fine wire inside called the filament. Electricity that passes through it heats the filament and makes it glow brightly. Originally made from carbon, the present day filaments are mostly made of tungsten wire which is more durable.
The colorful incandescent lights are the result of coatings on the inside of the bulbs.
Light Emitting Diodes (LED)
LEDs differ from incandescent light bulbs as they do not have a filament which can break or burn out. That simply means less maintenance. An LED is a small metal diode encased in a solid piece of resin with a couple of metal leads sticking out for contacts. Having no filament or glass bulb, the LEDs are extremely impact resistant and virtually unbreakable.
They do not produce heat and can last up to 100,000 hours.
Traditional bulbs produce heat from a glowing filament, wasting up to 80
percent of their power. LEDs need less power to produce light, which extends
battery life.
How LED Works?
Like all electronic diodes, an LED allows electricity to flow in only one direction. When the charged electrons move from the negative electrode (cathode) to the positive electrode (anode), parcels of light (photons) are released generating the bright and multicolor light we see. Under normal usage, LEDs can last between 1,000 to 10,000 hours.
What Are Semiconductor Materials?
A semiconductor is a material with varying degrees of conductivity – that
is, the ability to conduct electricity.
Through a process known as “doping”, poor conducting materials are turned
into semiconductors by the addition of impurities. In poor conductors, all
of the atoms are perfectly bonded leaving no free electrons to conduct
electric current. In doped materials, this balance is altered by the
addition of free electrons (N-type material, negative) or the creation of
holes where electrons move to (P-type material, positive).
In N-type material, free electrons move from a negatively-charged area to a
positively charged area. In P-type material, electrons move from hole to
hole, from a negatively-charged area to a positively-charged area.
Cathode (-)
Anode
(+)
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LED Is A Diode
A diode is made from both types of materials, a section of N-type material bonded to a section of P-type material, with electrodes on either end. This construction ensures electricity flows in only one direction.
How Is Light Produced In A Diode/LED?
When electrons move about, energy in the form of light is released by the
atoms. We know that electrons orbit around the nucleus. Electrons in
different orbital possess varying amounts of energy. Electrons that orbit
further away from the nucleus pack more energy.
When an electron moves from a higher orbital to a lower orbital, it will
release the excess energy in the form of light (photon). The greater the
orbital drop, the higher the energy of the photon, producing lights with
higher frequencies in the blue end of the spectrum.
How Colored Lights Are Produced In LED?
LEDs that produce visible light are made with a wider gap between the semiconductor materials. The size of the gap determines the frequency of the photon and hence the color of the light that is emitted.
LED In the Making of Flashlights
The design of the flashlight since its invention in 1897 has been greatly influenced by technological improvements in its major components such as the l.e.d. The decreasing manufacturing cost of l.e.d has made it commercially viable to produce l.e.d flashlights which are much brighter than the conventional incandescent light bulb.
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Batteryless rechargable flashlight uses LED, not light bulb.