Graphite powered garland
Ready to try some new wires for your holiday garland?
Warning! Only under adult supervision
- wooden holiday tree;
- soft pencil;
- battery pack with crocodile clips;
- AA batteries.
Draw the "wires": draw a continuous solid line along your holiday tree (it must be unbroken!). Connect a “+” crocodile clip to one of the legs of an LED (after checking its polarity), and a “–” clip to the lower end of the “wire.” Connect the free leg of the LED to the other end of the graphite "wire" and watch as it lights up!
The pencil lead is composed of graphite. A soft pencil allows you to draw a uniform, uninterrupted graphite line. Graphite can act as a conductor thanks to its unique layered structure, which gives its electrons the opportunity to move more freely than they otherwise would. This structure is very important – diamonds, which are also made up of carbon atoms, cannot act as conductors because they aren’t constructed this way! Interestingly, graphite’s conductivity also depends on the direction the electric current is moving: current can flow along graphite layers thousands of times more easily than perpendicularly to them.
A similar experiment can be found in the “Zinc-carbon battery” kit from the MEL Science subscription!