For over 400,000 years, humans have only had one method of generating light. Through the burning of organic materials, heat and light were generated. Over the course of the last century, we have learned that passing an electrical current through a resistor, a device that resists the passage of an electric current, also generates heat and light. This discovery has fundamentally changed how we act as a species. But in the last 20 years, LEDs have changed our lives in more ways than we ever thought possible. They utilize knowledge from quite a hot topic field: quantum physics.
Traditional incandescent lights, like the ones you might find in your grandparents' house or in your oven, heat up a resistor to produce light. This is a form of thermoluminescence (creating light from heat). LEDs, also known as Light Emitting Diodes, use electroluminescence (creating light from an electric current) as well as quantum physics–the study of how the world works on the scale of subatomic particles such as electrons and quarks, to generate light. Wait, are you saying that the new energy-saving bulbs that you bought work on quantum physics? Yes, they do.
An LED traditionally has two parts, a P-type and an N-type material. Both of these materials are semiconductors, meaning partially conductive, and determine the color of the LED. An N-type material has excess electrons and is thus negatively charged (electrons are the negatively-charged particles in an atom). Electrons in the N-type material have more energy. With that much energy, like little kids after a sugar rush, they'll want to get to rest after consumption. The P-type material has space for extra electrons. This creates a difference in potential energy across the two materials, known as bandgap voltage. Once the bandgap voltage is surpassed, energetic electrons from the N-type material flow across to the P-type material where they return to their resting state. As electrons return to their resting state they release energy in the form of photons (also known as light). Don’t worry, it’s not rocket science, it’s quantum physics! Hopefully, I mean unless you want your house to blast off into outer space.
LEDs are incredibly efficient as they convert electrical energy directly to light. They thus boast the highest lumen to watt ratio ever. What this means is that LEDs produce an equal amount of light as incandescent or fluorescent lights but use 5 times less energy. LEDs are among the brightest types of lighting out there. Well, minus screwing a miniature sun into the light socket. But we don’t really want to melt due to the sun’s heat. Unlike a mini sun, LEDs dissipate almost no heat and can be astonishingly small. This means that LEDs can be used in a variety of applications never dreamt of before.
Prior to the turn of the millennium, flat-screen TVs and monitors were only a faint dream and the typical display weighed upward of 50 pounds (22 kg). Now, you are most likely using a flat-screen LED display to read this article (thank you for reading!). LEDs require no housing and generate almost no heat. Because of this, it is possible to pack millions of LEDs into a small space. Each pixel on your screen is one tiny LED. What this means is that one of the newer 4k displays has over 8.25 million LEDs on it. Imagine that!
An LED bulb might contain 50-100 single LEDs. A single LED is not very powerful. And that’s why multiple LEDs are packed into one bulb. This makes it possible for LEDs to become extremely bright. As there are multiple LEDs in each light bulb, it can last for 25,000 hours without needing to be replaced.
LEDs have revolutionized the way we live in a very short period of time. They have sparked incredible innovation. Over the course of two decades, LEDs have drastically increased the efficiency, power, and possible applications of manmade lighting. Through science, LEDs have brought around a new era. As we unravel the secrets of the universe, how else will our lives change?
Post By: Armaan G.
Photo Credits: Piccolo Namek, CC BY-SA 3.0 <http://creativecommons.org/licenses/by-sa/3.0/>, via Wikimedia Commons
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