Friday is here, and with it the weekly "A Taste of Physics" column — number 37.
This week: the connection between a pickle, an electrical circuit, and street lamps.
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The video shows what happens when an electric current is passed through a pickle.
Not only does it conduct electricity — it also emits light.
Why does this happen?
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During the pickling process, the cucumber is soaked in a highly concentrated saltwater solution.
Salt crystals contain sodium and chlorine arranged in an ordered crystalline structure that prevents them from moving freely.
Dissolving the salt in water breaks it apart into positive sodium ions and negative chloride ions, turning the water into an electrolyte — a substance that allows electric current to flow through it.
When electrodes are attached to the pickle, an electric current flows through it. The positive ions are attracted to the cathode (the negative electrode), and the negative ions to the anode (the positive electrode).
As the current flows, the sodium ions become "excited" — the energy added to the electrons orbiting their nucleus causes those electrons to orbit at a greater distance.
The ions then "cool down" and the electrons return to their original orbitals around the nucleus, releasing the excess energy in the form of a photon of light.
Sodium ions emit light at a frequency corresponding to 589 nm — a wavelength our eyes perceive as yellow-orange light.
The "smoke" is actually water vapor, produced by the heat generated during the process.
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Sodium is also used in old-style street lamps.
They contain sodium in gas form, and the electric current passing through it produces the same familiar orange-yellow glow.
Shabbat Shalom 😊
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