We know that graphite conducts electricity. We’ve likely had to change the graphite brushes in a simple electric motor at some time in our lives. We also know that graphite makes a great anode in a lithium battery because it is freely able to accept and release ions. In this experiment we are going to demonstrate how black pencils conduct electricity too.
A Bizarre Possibility: Could Diamonds Conduct Electricity?
We’ll assume they don’t use diamonds for battery anodes because they are expensive although they are also made of carbon. However, diamonds would not actually work either, because their carbon structures are different from those of graphite. That’s because nature forms them under great pressure as carbon emerges from Earth’s core.
Thus diamonds comprise a three-dimensional lattice arrangement in which each carbon atom bonds to four other carbon atoms. This keeps the electrons firmly in place, which is why an electric current cannot flow through them. Whereas two-dimensional graphite allows the electrons to flow freely. So for this experiment you are going to need a black lead pencil, not Mum’s diamond ring.
Let’s Do It. Pass Electricity Through a Pencil.
Pencils Conduct Electricity and Act as Resistors Too
The light bulb dimmed and brightened as the distance varied between the points on the pencil where the battery wires connected. That’s because the resistance varied as the person in the video moved them further apart and then back together again.
Electrical resistance is the extent to which an object resists the flow of electric current through it. For example, glass and rubber resist electricity completely, whereas graphite cores in pencils conduct it as we just saw in the video. It’s important to match the resistance of a device with the energy contained in the battery to which it connects.
The person in the experiment chose wire and a light bulb with resistance to suit the battery. If they had not, their experiment would have failed, or the light bulb might have popped.
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Video Share Link: https://youtu.be/AdMmQbyCdYg
