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The Transition From Incandescent to LED Bulbs

—Houston, Texas

The twinkling lights hung for the seasonal holidays have made their dramatic appearance in people’s yards and trees. Nowadays, many stringed lights are LED lights, which stands for Light Emitting Diode. Before LED lights, incandescent lights were used, which use high temperatures to excite electrons and create a warm, orange tint. These lights each have a thin tungsten filament that is enclosed by a glass globe. Argon gas makes up the inside of most of these bulbs. If there is oxygen inside the bulbs and reaches the hot tungsten filament, the filament undergoes rapid oxidation and gets destroyed. As a result, incandescent bulbs do not have a long lifespan because oxygen is present in the air and gradually seeps into the bulbs, which breaks down the filament and can no longer conduct electricity—at that stage, the bulb is “burnt out.” Because heat is emitted, a lot more energy and electricity are required to produce light in incandescent bulbs. Unfortunately, more than 95% of energy used is lost as heat and less than 5% produces light. Therefore, these bulbs are being replaced by more energy-efficient light sources around the world.


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Diagram of an incandescent bulb

In comparison to incandescent bulbs, LED bulbs are more energy efficient because they do not lose much energy as heat and use significantly less electricity to produce light. Diodes are devices that allow electric charge to flow in one direction, called a direct current. Light is produced when an electric current is passed through the LEDs. LEDs have two semiconductive layers—the n-type, which contains excess electrons, and the p-type, which contains “holes” where the electrons could be accepted. Once a voltage is placed across the semiconductor layers, the electrons will be excited and cross from the n-type to the p-type layer to fill the holes. When the holes are filled, it causes the electrons to deexcite and lose energy in the form of a photon of visible light. In addition, the color of the light produced by LEDs is based on the material the semiconductor is made of, specifically depending on the depth of their energy “holes.” A larger drop in energy creates higher energy photons, producing a color that is more blue, whereas a lower drop creates lower energy photons, producing a color that is more red.


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LED bulbs are able to emit light when electrons get excited and are received by the holes

LED bulbs last forty times longer than incandescent bulbs and are more environmentally friendly because of their efficiency in energy. Since LED lights are more energy saving, they are cheaper for people to use. Because of this, LEDs have recently been used more often in a variety of applications, including holiday decorations.


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