Science Buddies: "Ask an Expert"

I am makeing a MFC and i was wondering about a few things. #1 do the anode and cathode wires need to be conected even when im not takeing readings? i thought that the anode and cathode electrodes would have to be conected for the electrodes to get from the anode chamber to the cathode chamber. please help! =]#2 if i attach a light bulb inbetween the anode and cathode wires will the electron current make it light up?

justin-sickly wrote:#1 do the anode and cathode wires need to be conected even when im not takeing readings?

You only want to complete the circuit when you want current to flow through a useful load. Shorting them together serves no useful purpose other than depleting the fuel.

justin-sickly wrote:i thought that the anode and cathode electrodes would have to be conected for the electrodes to get from the anode chamber to the cathode chamber

Electrons flow from the anode chamber to the cathode chamber internally in the fuel cell. The cathode is where the electrons collect so it has a negative charge. Making an external connection between the cathode and anode allows the electrons that the fuel cell pumps to the cathode to flow to the anode where they are pumped internally back to the cathode to complete their path.

justin-sickly wrote:#2 if i attach a light bulb inbetween the anode and cathode wires will the electron current make it light up?

Maybe. If the open circuit voltage of your MFC is appropriate for the light bulb you choose and the MFC is capable of producing enough current for the load the light bulb imposes, then it should light.

If the MFC produces a significantly higher open circuit voltage, you will probably burn out the light bulb. If the bulb has a higher voltage rating than the MFC, it may or may not light dimly.