Making spirits bright with the science of Christmas lights

by perducoeducation

My favorite part in the movie National Lampoon's Christmas Vacation is when Clark Griswold’s 250 strands of lights on his house finally turn on. If you haven’t seen Christmas Vacation, Clark decorates his entire house – and I mean the ENTIRE house – with Christmas lights. He brings out his whole family to see the lights all turn on at once. But, as he brings the two power cords together to turn it on, nothing happens. Later, after his wife flips the correct switch, all the lights flicker on, lighting up basically the whole city. A Christmas miracle!

Although we might not go as all out as Griswold on our Christmas lights, they’re a key piece in building the holiday spirit. And, as we’re getting into the holiday cheer here at Pitsco, what better way to brighten our spirits than by learning about how these lights work?!

How Christmas Lights Work

Christmas lights can teach us a whole lot about the flow of an electric current. Voltage and current are two words that come into play with lights. Voltage is what makes electrical charges move; it’s what helps push the charges to move in a wire, whereas current is the number of electrons flowing through that wire.

When you plug in your Christmas lights at home, the current is what changes. The more light bulbs you have on your string, the more current you will be sucking out of your wall socket. Now let’s get to the fun part – how the lights get their glow!

After the lights are plugged in, electricity travels through a closed circuit and passes over a filament to cause the light to glow. A closed circuit is like a bridge over water; the bridge helps the car drive over the water and continue on the road. A closed circuit allows electricity to flow without an interruption. The more current that passes over the filament, the hotter the light will get, the brighter it will be, and, in the end, the quicker it will burn out. When the filament becomes burnt, the closed circuit is broken, creating an open circuit.

So, now you want to see if you can upstage Clark Griswold by hanging lots of lights on your house, right?! Well, first, you’ve got to learn how to connect multiple light bulbs to the same power source. There are two ways to do this: in series or in parallel. In a series circuit, the bulbs are set up one after another on a wire, so the electricity passes from one light to the next and so on. But, when a filament burns out and the circuit becomes open, electricity fails to pass through any of the wire and the dreaded happens: all the lights go out. A parallel circuit is where each light has its own circuit to the power source. When one light burns out, it only affects that light, saving you time and stress!

Light Show ­

During the holidays, we love to jump into the car to ooh and aah at all the lights around town. But, my favorite is when we come up to a house that’s displaying a light show that is synced up to music! If you’re that house, I applaud you! I’ve never quite figured out how that actually works – it’s just magic, right? Well, while most of Christmas is magic, I’ve learned that the lights that are synced to the music require lots of light bulbs, control circuity, and sequencing. If you have the time, check out this amazing light show!

The Tech Support Guy created a video and explanation of how he sets up his own light show. He shares that he purchases a whole lot of special LED lights that each contain a microchip, allowing him to program each individual bulb versus each strand of lights. For example, with the special LEDs, you can light up letters or create different designs.

These smart LEDs are all hooked up to a controller, which sends them commands. The controller gets data from a computer and then pushes it out to each bulb. The brain of the whole show is the computer. The Tech Support Guy uses an open-source computer board that sends each song’s program to the controller.

After you’ve got all the hardware set up, it’s now time to sequence your lights using your computer! The Tech Support Guy uses a platform called xLights, which is a free, open-source program that enables you to design and create your light show. You’re able to draw out exactly where your lights are, design effects for lights, and then place them on a timeline of the song. Setting up this sequence takes a lot of time and planning, but it’s all for the spirit of the season!

Light Up Your Own Tree

Bring the lights to your kiddos! Try some of these Christmas light projects:

Or, just learn more about electricity with these shockingly fun activities:

We’d love to see your lights or holiday projects you’re doing – be sure to tag us on social! Wishing you the happiest of holidays!


The Science of Christmas Lights

How Do Holiday Lights Work?



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