the potentials of using led as commercial light

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    LED as Commercial Light Source

    Physicsis UM

    Prosacks UM

    http://prosacksblog.blogspot.com

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    Introduction

    Q: What is LED?

    A: LED Light Emitting

    Diode

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    Basic Principle of LED

    Basically, an LED is just a special type of diode.

    Diode is the simplest sort of semiconductor

    device.

    Most semiconductors are made of a poor

    conductor that has had impurities (atoms of

    another material) added to it.

    The process of adding impurities is called

    doping.

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    Basic Principle of LED

    A semiconductor with

    extra electrons is called

    N-type material.

    In N-type material, freeelectrons move from a

    negatively charged area

    to a positively charged

    area.

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    Basic Principle of LED

    A semiconductor withextra holes is called P-type material.

    Electrons can jump from

    hole to hole, moving froma negatively charged areato a positively chargedarea.

    As a result, the holes

    themselves appear tomove from a positivelycharged area to anegatively charged area.

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    Basic Principle of LED

    Now, lets see the basicworking principle of LED.

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    Basic Principle of LED

    At the junction, free

    electrons from the N-

    type material fill holes

    from the P-typematerial. This creates

    an insulating layer in

    the middle of the diode

    called the depletionzone.

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    Basic Principle of LED

    When the negative end

    of the circuit is hooked

    up to the N-type layer

    and the positive end ishooked up to P-type

    layer, electrons and

    holes start moving and

    the depletion zonedisappears.

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    Basic Principle of LED

    When the positive endof the circuit is hookedup to the N-type layerand the negative end ishooked up to the P-typelayer, free electronscollect on one end ofthe diode and holes

    collect on the other. Thedepletion zone getsbigger.

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    Basic Principle of LED

    In the LEDs, the conductor material is typically

    aluminum-gallium-arsenide (AlGaAs).

    In pure aluminum-gallium-arsenide, all of the

    atoms bond perfectly to their neighbors,

    leaving no free electrons (negatively charged

    particles) to conduct electric current.

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    Basic Principle of LED

    In doped material, additional atoms change

    the balance, either adding free electrons or

    creating holes where electrons can go.

    Either of these alterations make the material

    more conductive.

    The interaction between electrons and holes

    in this setup has an interesting side effect -- it

    generates light!

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    Basic Principle of LED

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    Basic Principle of LED

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    Basic Principle of LED

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    LED Lamp in CommercialUse

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    LED Lamp in Commercial Use

    LED lamps which are used comercially usuallyconsist of three parts, ie;

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    LED Lamp in Commercial Use

    The LED that emitting

    light

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    LED Lamp in Commercial Use

    The lens which focusing

    and aim that light.

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    LED Lamp in Commercial Use

    Heat sink draws heat

    away from the lamp,

    keeps them from

    overheating.

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    Now, lets look at some benefits of

    using LED lamps as the major light

    source in daily life.

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    1) Longer lifetime

    Good quality LED lamps

    can have a lifetime up

    to 50,000 hours.

    Incandescent bulb (bulbwith filaments) 1,000

    hours.

    CFL (compact

    fluorescent lamp)

    10,000 hours.

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    1) Longer lifetime

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    2) Energy Efficient

    Less energy needed to

    light them, thus, cutting

    cost, and environment

    friendly.

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    3) Non-hazardous

    LED lamp do not contains mercury as in CFLand fluorescent lamp.

    Safer to be used at home.

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    Disadvantages

    More expensive as the cost of production ishigh, however, in long-term usage, it isactually will save a lot of maintenance cost.

    Vulnerable to high temperatures. If LEDcircuitry gets too hot, more current will passthrough thejunction mentioned earlier in thisarticle. When too much current coursesthrough the junction, it will cause irreversibleburn-out often called LED meltdown.

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    Thank you for listening.

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    References:

    http://electronics.howstuffworks.com/led.ht

    m

    http://www.youtube.com/watch?v=vDYZxWN

    Dm4k

    http://electronics.howstuffworks.com/led.htmhttp://electronics.howstuffworks.com/led.htmhttp://www.youtube.com/watch?v=vDYZxWNDm4khttp://www.youtube.com/watch?v=vDYZxWNDm4khttp://www.youtube.com/watch?v=vDYZxWNDm4khttp://www.youtube.com/watch?v=vDYZxWNDm4khttp://electronics.howstuffworks.com/led.htmhttp://electronics.howstuffworks.com/led.htm