electric from the potato

food hand organ electronics finger potato battery electric measuring voltmeter electrical voltage millivolts levels bio 91 potato potatoes-cell potato-battery 0-91volts acid acidic-electrolyte amper anode battery battery-types bio bio-battery bio-cell energy capacity cathode chemical-reaction chemistry copper copper-electrode digital education electric-current electrical electricity electrolyte energy-source energy-storing experiment ions lab laboratory laboratory-experiment measurement measuring-instrument millivolt multimeter physics renewable school-experiment school-laboratory separator sulfuric-acid voltage voltmeter zinc zinc-electrode zinc-metal low-current dc-voltage