Electric Pickle
Overview: Atomic emission spectra are unique spectra of light emitted by an element when electricity is applied. A pickle produces an emission spectrum with primarily one line from the sodium doublet at 589nm.
Supplies: Pickle, pickle mount, paper towels
Objectives: How can you make a pickle into a lightbulb? What are emission lines?
NOTE: The demonstration must be led by an adult and everyone must stay back and out of arm’s reach. Do NOT try this at home. BE VERY CAREFUL.
Setup:
- Be sure that your area is clear and children are out of arm’s reach from the source of electricity.
- The pickles will produce a strong odor once electrocuted, so consider a ventilated area.
- Take a pickle and place it on the mount such that the two electrodes are completely inside the pickle.
How to run the demo:
- Flip the switch on the power supply.
- After a few seconds, you should start to hear some sizzling, and then the pickle will glow!
- Depending on the size and the moisture contained, the pickle will continue to glow up to a minute until the light starts to sputter out and smoke will be produced around the electrodes.
- TURN OFF THE POWER BEFORE TOUCHING THE PICKLE.
- You can reposition the pickle on the electrodes and try again, or replace with a new pickle.
What’s Happening?
Pickles contain salt, both sodium (Na+) and chloride (Cl–) ions. Applying electricity excites the sodium electrons, which then emit light as they relax back to their ground state. The yellow light produced is unique to sodium, and is the same color as the sodium vapor lights often used as street lamps (shown below).
Just as sodium atoms produces yellow light when excited, different atoms produce different wavelengths of light called emission spectra. Astronomers can use the emission spectra of faraway stars to determine their composition.
Try this:
- Use diffraction glasses and look at the spectrum of the glowing pickle compared to a sodium lamp.
- Use a spectrometer to verify the wavelength produced by the sodium emission.
- Try soaking pickles with different ions to create different atomic emission lines.
- Try soaking different vegetables in sodium or other ions. In our tests, Daikon radishes were most effective.
Troubleshooting:
- If flipping the switch does not produce any sound, smoke, or light out of the pickle, turn off the switch and press the reset button on the ground fault circuit interrupter (GFCI). This can be tough, so use a key or something pointed to press the reset button down until you hear a click, and then try again.
To learn more: (external links)