BILLIE: I gotta right to sing the blues, I gotta right to moan inside …

I gotta right to sit and cry, down by the river …

ADABOT: Whoa! What’s that music?

RUBY: That’s just Billie!

ADABOT: Really? - she sounds kind of sad …

GUS: Yeah, don’t go nuts. Billie’s just got the blues again.

ADABOT: Ohhhh …

ADABOT: Hey Billie, Why so blue?

BILLIE: I suppose that’s just the way I am. 

ADABOT: So, you’ve always been blue?

GUS: Yeah, well - she’s made with Gallium Nitride.

ADABOT: Gallium what? What are you talking about?

RUBY: Well, Adabot - inside every LED is a small crystal

ADABOT: Oh, really …

RUBY: When you connect the short leg of an LED to ground, and the longer leg to positive voltage - voila!

GUS: The crystal glows and the LED lights up!

ADABOT: Very cool - so when electricity flows through an LED’s crystal, it creates light! But why are LEDs certain colors in the first place?

RUBY: The type of crystal used in an LED determines that LED’s color.

ADABOT: Oh - interesting!

RUBY: A red LED like me uses a type of crystal made of Gallium Arsenide - that’s two elements, Gallium and Arsenic, mixed together.

GUS: I use an Aluminium Gallium crystal to get so green.

BILLIE: and Indium Gallium Nitride is what makes me so blue.

ADABOT: Oh - so different crystals make different colored light!

RUBY: Yeah!

ADABOT: But I’ve also seen LEDs that change color? How do they do that?

RUBY: Well, we usually call those color-changing LEDs – RGB LEDs.

BILLIE: Hey - I’ve got an RGB LED here.

RUBY: Oh good - Let’s take a closer look to see how they work …

RUBY: We call them RGB because inside every one of them are three different types of crystals - one that makes red light, one that makes green light, and one that makes blue.

ADABOT: ohh, R - G - B – red, green, blue!

RUBY: Exactly - and by mixing red green and blue - we can make pretty much any color we want!

GUS: like, say - purple

BILLIE: or orange

RUBY: Or even white!

ADABOT: Wow - thanks, guys! LEDs make a lot more sense now!

RUBY: You’re very welcome, Adabot. LEDs are in so many electronic devices, screens, billboards, – even light bulbs

BILLIE: It’s really important to understand how they work!

ADABOT: You know, Billie - you may be blue, but you light up my life.

GUS, RUBY, BILLIE: Awwwwwww …

This guide was first published on Jun 01, 2017. It was last updated on Jun 01, 2017.

This page (Transcript) was last updated on Oct 25, 2020.