Mud+Battery

Mud Power:
We were able to create a functioning battery using a jar of mud, graphite and wires.




 * How it works**: The graphite forms the anode and the cathode. The anode is placed near the bottom of the jar, while the cathode is placed on top. The anode is an anaerobic environment, which contains certain strains of bacteria. These bacteria produce type of molecules called 'reduced compounds,' basically bio-molecules that have extra electrons. These gather near the anode, which becomes negatively charged, creating a voltage drop across the two wires. Once the electrons travel to the cathode, they are finally accepted by oxygen, and create water as a by-product. The bacteria eat food in the soil, and they are the ones that produce the voltage differential. It's not a chemical reaction, but a biological one, and so the __#|batteries__ recharge themselves over time.


 * Notes to students**:
 * Graphite or aluminium foil work as nodes, but graphite won't oxidise
 * More surface area seems to be better
 * It's best to keep the dirt moist, about as damp as mud in a swamp. But there should be no visible water.
 * The voltage ranges from 0.2V to 0.4V, to 0.7V in really good cells
 * Batteries in series compound the voltage...just saying...
 * Decreasing the battery's internal resistance allows them to supply more current, and increases the voltage
 * What's internal resistance? Here.
 * How do you decrease it? Keeping the dirt moist, and adding __#|electrolytes__.