Use the parts to complete the circuit, and if you’ve done it all right, your LED should light up! Remember that the longer leg of the LED is the positive end (Anode) and the shorter one is the negative end (Cathode). If the LED does not glow, reverse the connection and try.
What if you wanted to display multiple LEDs, all at once? Connect them in series by connecting one LED’s anode to another’s cathode…but you need to make sure you supply the correct voltage as well - For each LED, provide 3V.
The LED has a piece of material specifically created to have have “holes” and “electrons”. A “hole” is a where an electron used to be, but does not exist right now. And an “electron” here refers to an “extra” electron that’s been added in through a process called “doping”. Under normal circumstances, the holes and electrons stay apart because of an electric field between them that keeps them apart.
By applying some forward voltage, you can push some of the electrons towards the holes, and vice versa. When an electron takes the place of a hole (which happens at the p-n junction), the electron moves into a lower energy state, causing it to give off some of it’s excess energy. This “energy” is electromagnetic radiation, given off in the form of photons. If amount of energy released is less, the color we see is red. If the amount of energy released is high, it will appear blue. (Of course, here less and more are just relative terms)
This can also be explained from a “wave” standpoint. Light is a combination of different wavelengths (corresponding to different energy levels). Now when the electrons move into holes, they emit waves of different wavelengths, depending on the amount of energy released. This site gives a nice list of colors, by wavelength.
Benefits of LED
Before LEDs came along, the world was lit by Edison’s light bulb - which created light, but also generated a lot of heat which was wasteful use of energy. LEDs can generate light, without causing much heat and therefore use much less energy when doing their business of lighting up our lives.
Less wasted energy means less plundering of the natural resources which means an Earth that can last longer.
History (and colors) of LED
First, there was the red LED. Then green, and then after a 30 year gap, the blue LED. It was the last to be manufactured, and it was the one that finally enabled “White light!”
The elements used to create differently colored LEDs.