Monthly Archives: March 2014

Light Emitting Diodes (LEDs)

Notice anything different about bike lights recently? Just walking back from somewhere at night when you see a car coming towards you with beaming headlights approaching as cross the road. As this vehicle comes closer, you see that it’s not a car but actually a harmless cyclist. You’re confused on how a light small could produce such brightness.

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Well, due to a improvement in modern technology LED lights have become more efficient. These light emitting diodes which usually power bike lights now produce a lot more light energy instead of heat energy so the bulbs are much brighter as a result.

So, how does a LED emit light? Let’s start from the beginning, the usual filament lamp, also know as a an incandescent light, becomes bright when the piece of wire becomes hot due to electricity flowing through it.

Without any filament inside it, how does an LED light work? Well, it’s because of the movement of electrons in a semiconductor inside the light. Light can be emitted in a wave or particle form and in this case the light is emitted as a particle. With pin the LED there are many atoms and the electrons are constantly moving between the electron shells, this gives off energy. So, this energy produced is in the form of a photon, a particle of light. For the light to be visible, the diode must be made out of a material, for example a silicon diode is made so the electrons only travel short distances meaning that the photons have a low frequency making the light emitted visible to the eye.

In the house, however, it’s a bit of a different story. LEDs only work off direct current and the houses electricity is alternating current so to gets the bulbs to work the ac must be converted to dc. This means that LED bulbs are less efficient in the household because of the energy that is used to transform the current. This shows that although LEDs are extremely useful in some ways, on a bigger scale they do become less efficient.