Circuits have a few main components, batteries to provide power, wires (or in our projects copper tape) to act as a roadway for electrons, and a switch to control the flow of electrons.
Why do paper circuits need copper tape?
All circuits need a highway for the electrons to flow through. In regular circuits, we see these highways as wires. In paper circuits, however, we want our highways to be flat, so we use a special type of tape.
Copper is a conductor, which means it allows electrons to flow freely through it from place to place. Where you lay down the copper tape is the path that electrons can take. If you put the copper tape to an LED, then electrons can move to that LED, if you put it to a speaker, then they can move to the speaker.
Why does copper conduct electricity?
In all of our paper circuits, we use copper tape. This is because the copper tape is easily accessible (you can find it at the garden store to repel slugs) and cheap. Oh, did we mention, copper conducts electricity? That is the more important quality of the copper tape. In fact, we could use any metal to connect our paper circuits, copper tape is convenient because you can stick it down to the paper and your parts, and it requires no soldering.
But why does copper conduct electricity? For that matter, why do all metals conduct electricity? It comes down to the types of bonds that metals make. Metals make incredibly strong bonds with each other, which allows electrons to run free through them as if they are high ways. In addition, the outer electron shell of copper (and many metals) is only partially filled. For copper, the outer valence shell is only half full, which allows more electrons to freely move around instead of being tightly bound to their nucleus.
Can I add anything else to my light up cards?
Light up cards are super cool. Once you get the hang of them you might find yourself, or your kids, asking if you can add music or a tiny motor to your light up card.
Let’s be honest, who doesn’t love a light up card that can also play music? Yes, you can do that. You can find complete soldered kits with adhesive backing on Amazon, which means all you have to do is peel and stick it to your light up card to add this functionality.
You can also get the chips unwired, but you’ll need to learn soldering to make these a reality.
Why does the direction of the LED matter in my light up card paper circuit?
LEDs make light when electrons go from a higher energy state to a lower energy state. As they slide down to the new state their excess energy is released as light. The farther they fall the bluer the light is. You can imagine then if they aren’t sliding down, but trying to go up, they won’t have any excess energy to shed as light.
In that way, you can think of LEDs as playground slides. Electrons are really good rule followers so they won’t go up the slides. If you have your LED in backward, you are basically piling up electrons at the bottom of the slide.
What is it like to be an electron in a circuit?
You can find out! We have created an electric circuit obstacle course that lets you run around a playground circuit just like electrons do!