What is an LED?
Hi there! My name is Ed. I’m an LED. The name LED stands for “Light-emitting Diode.” That may sound a bit confusing, but it’s actually pretty simple.
Light-emitting means that I shine when a current of electricity passes through me. If you give an LED some power, it shines nice and bright.
And a Diode is an electronic gizmo that only allows electricity to flow in one direction, in through one of my legs and out the other. I’m kind of like a valve with a little wall that lets electricity flow forward, but not in reverse.
There are lots of kinds of diodes out there, but I am the only type that shines a light.
LEDs come in lots of shapes and sizes. Some have small round heads, and some have large heads. Some are tiny and look like boxes. But we all shine bright lights.
LEDs also come in lots of different colors.
Single Color LEDs
Some LEDs, like me, shine only one color. You can tell which color from the plastic case around our heads. My head is green, so I shine a green light. An LED with a red head shines a red light. What color do you think comes from an LED with a blue head? That’s right, blue!
Single-color LEDs like me have two thin metal legs — called “leads” — and one leg is longer than the other. The longer leg is my “anode” and is the leg I always point towards my power source. That’s why its called the positive leg. My shorter leg, or negative lead, is the “cathode” and always points toward the end of the circuit. That’s where I send power after I’ve used it to light up.
If you get up close and look at an LED like me, you might notice that one part of the base of my head sticks out like the bill of a baseball cap. That part is always on my positive side, or the side with my longer leg.
Multi-Color LEDs
There are some LEDs that are very special because they can shine any color you can imagine. These are RGB, or red-green-blue, LEDs. They have that name because they have three little LEDs inside of them that can shine the colors red, green and blue. Their cap is clear so the colored lights inside can shine through.
Making colors with this type of LED is a lot like mixing paint colors together to make new colors. Imagine that you have a plate with blobs of red, green and blue on it. You can even try this out yourself! Now, imagine that you take a small bit of red, a bigger amount of blue and a large amount of green and mixed them together. What color do you think you would get? Depending on how much you use, you’d end up with a dark blue color.
RGB LEDs work exactly the same way. If you shine the red light a little, the green light a bit more and the blue light a lot, you’d get a blue light. But it would be a darker blue than if you shined the blue light by itself. This is because of the green and red light that mix with it.
So how do you light up an RGB LED? Just like single-color LEDs, like me, it’s all about the legs. Notice anything unique in the picture here? RGB LEDs are special because they have 4 legs instead of two. Three of those legs control how bright to make each light in the LED. Red is the shortest, blue is a bit longer and the green leg is the longest of the three. The more power you give to each leg, the brighter its red, green or blue light will shine.
The fourth leg, longest of all four legs, is the positive, or anode leg. Like my longer leg, it points towards where power flows into the circuit provides current for lightning up the diodes inside.
LEDs are all around you
I think LEDs are the most exciting part of electronics because you can find them everywhere. You can find them in clocks, in your TV and your video game console. You may also find them in the lightbulbs in your house!
In the world around you, LEDs are easy to spot. You can see them in string lights at night, in the big screens at soccer, baseball or football games and in signs on the highway.
It’s fun to look for LEDs and discover how important we are to the world. What things can you find around your house that use LEDs? What about at school, or when you’re out with your family?
Thanks for reading about me, Ed the LED! Next time, my good friend Patty will talk about the capacitor, so we hope you’ll come back soon!
Also, my friends and I are being featured in a book that will be coming out later this month! You can find out more about it here, and tell your parents to sign you up to you can find out when the book is released!
