Electrocute a Pickle

Materials Needed:

  • large Dill pickle
  • 2 ring stands
  • 2 clamps for the ring stands
  • 2 screws
  • 1 extension cord
  • electrical tape
  • variac ****absolutely necessary!! DO NOT attempt this activity without this!

Procedure:

NOTE!!!!!!! DO NOT TRY THIS ALONE! This should NOT be done at home and needs lots of adult supervision. Even adults should have buddies with them to make sure they don’t get hurt!!!

1. Make sure the extension cord is NOT plugged in. Cut the end of the extension cord with all the outlets on it. Split the 2 wires and wrap each exposed wire around a screw. Secure with electrical tape.

2. Set the ring stand up about a foot apart. Secure one screw in each clamp and have the screws facing each other.

3. Put the pickle in place. One screw should go in each end of the pickle. MAKE SURE THE SCREWS DON’T TOUCH-THEY WILL ARCH!!!!

4. Make sure the variac is set at 0, is switched off and unplugged. Plug the extension cord into the variac. Plug the variac in.

5. Turn the variac on and SLOWLY turn up the voltage to 120 volts.

6. At first, the pickle will start dripping. Then it will start to hiss and smoke and then it will really start glowing. And it will smell!!! Make sure you unplug the unit before removing the pickle.

What’s Happening?

It seems it's not actually the pickle which is glowing. It's the pickle vapor. See, the current heats the pickle juice (which is mostly brine and vinegar) to above boiling at the points where the electrodes are inserted into the pickle. While it's hot, the vapor is invisible. But as it cools, it emits light. So, they're actually illuminating pickle gas. Who knew?

While the exact mechanisms are unclear, our observations lead us to propose the following model of light generation. Upon initial application of power, the pickle conducts strongly. This is not surprising since the pickle is thoroughly impregnated with a highly ionic sodium chloride salt solution. Resistive losses cause the pickle to heat. One would expect the heating to be the greatest in the vicinity of the electrodes where the current flux is highest.

When the temperature at the surface of the electrode reaches about 100 degrees C, boiling occurs. The water vapor generated locally blankets the electrode. This vapor is non-ionic and not conductive, and if sufficiently thick, current can no longer flow from that point on the electrode surface. Of course as soon as the local current flux ceases, the heating at that point ceases as well, at the area begins to cool. When the area has cooled sufficiently, the vapor blanket collapses and conduction and heating resume. At some point during the transition to or from the conducting condition, an arc is supported and light is produced. It appears that a quasi-equilibrium state is reached providing a relatively steady light source. The composition of the plasma in the arc is not known but may contain hydrogen (from decomposition of water and the sample's organic constituents), carbon (from the sample), and various atmospheric gases. A spectroscopic observation of the arc, perhaps through a fiber optic probe, would help elucidate the composition.