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Physics/ionizing air measurements


would an electroscope be useful in detecting air ionization from a negative ion ionizer? if i put it near the output of the ionizer would some of the negative ions transfer their charge to the rod and leaves. i just am not sure if there is a reason for the ions to do so as the electroscope terminal is not grounded and as soon as a few impart a charge the rest will be repelled away. maybe i could use a metal tube connected to the electroscope terminal and blow the ionized air through the tube using the feraday ice pale effect to build up charge?
thank you,

Hello gene,

I have found many web sites that discuss the use of an electroscope to detect positively ionized air. I will list some below. The electroscope is initially given a negative charge. The electroscope indicates the presence of positively ionized air by discharging much faster than it otherwise would. The positively ionized air discharges the electroscope by accepting electrons.

I can't think of any reason that negatively ionized air would not donate electrons to a positively charged electroscope. However, I have not confirmed it. (The 3rd link in the list below takes you to a site that does vaguely indicate that it could work both ways.)

The web sites that I found:

I hope this helps,


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Steve Johnson


I would be delighted to help with questions up through the first year of college Physics. Particularly Electricity, Electronics and Newtonian Mechanics (motion, acceleration etc.). I decline questions on relativity and Atomic Physics. I also could discuss the Space Shuttle and space flight in general.


I have a BS in Physics and an MS in Electrical Engineering. I am retired now. My professional career was in Electrical Engineering with considerable time spent working with accelerometers, gyroscopes and flight dynamics (Physics related topics) while working on the Space Shuttle. I gave formal classroom lessons to technical co-workers periodically over a several year period.

BS Physics, North Dakota State University
MS Electrical Engineering, North Dakota State University

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