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MIT Physics Demo -- Conductivity of Ionized Water

A light bulb is placed in series with two copper plates immersed in de-ionized water. Touching the plates closes the circuit, lighting the bulb.

When kosher salt is dropped into the de-ionized water, the salt dissolves, causing ions to be dispersed throughout the liquid. The free ions allow current to flow through the water, which completes the circuit and lights the bulb.

Most water we encounter in everyday life is not de-ionized and contains impurities with dissolved ions. This is why we know water as a good conductor, and why we shouldn't use electronic devices around a bathtub, for example.

Comments (5)

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Posted almost 9 years by Anonymous User

Great demos. Unfortunately, you will get some whackos purporting your scientific demonstrations as proof of their crackpot pseudo-scientific thinking. Keep up the good work.

Posted almost 9 years by Anonymous

Great demo. In my work I get to simulate intermittent arcing faults on electricity networks, and I use a bucket of water with salt dissolved in to to do this.

Nice work, and I agree with watching out for the pseudo science!

Posted almost 9 years by Anonymous

Thank you for this great demo!! Besides conductivity, ionized water has many health benefits. For more information, visit

Posted over 8 years by KangenWaterReport

i’m wondering a much bigger question! whats different about it being “kosher salt”? would sodium chloride not work just as well? ;) and does the de-ionized water need to be kosher?

Posted over 6 years by skinnchip

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June 20, 2008 16:53
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