With a pencil?

As you can see in Paper Drawn Circuit you can make a simple circuit just with a soft pencil. It’s as easy as it sounds.Just draw a a path to connect the battery and the led and it’s done. But how it works?, and, why is not widely used, instead of copper?. Lets try to answer.

How it works?

Pencils are made with [graphite] (https://en.wikipedia.org/wiki/Graphite), a carbon based mineral, and is able to conduct electricity.

Why is not widely used?

Well, that’s easy. If you try the experiment, you may notice we are using a 9v battery, and the led is not glowing a lot. In other experiments you can lit more than one led with just one 3v battery. It’s like transporting water with your hands, you can do it, but you need so much effort to fill a simple glass of water.