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# Physics/Air resistance to electricity?

Question
How many volts are required to pass through let's say a hundred meters of air?

Well, air will conduct some small amount of electricity at any voltage.  Air is not some perfect resistor.  However, if you're referring to the dielectric breakdown strength of air, it depends greatly on factors like how dry the air is.  In dry air, it's quite high.  The generally accepted factor is about 3,000,000 volts per meter.  That would mean that 100 m of air would require 300 million volts to make a spark.  In practice, damp air (like in a thunderstorm) breaks down quite a bit more easily under high voltage and the voltage associated with things like lightning bolts are far lower.  A towering thundercloud is, however, capable of producing voltages in the 100 million volt range.

Physics

Volunteer

#### Dr. Stephen O. Nelson

##### Expertise

I can answer most basic physics questions, physics questions about science fiction and everyday observations of physics, etc. I'm also usually good for science fair advice (I'm the regional science fair director). I do not answer homework problems. I will occasionally point out where a homework solution went wrong, though. I'm usually good at explaining odd observations that seem counterintuitive, energy science, nuclear physics, nuclear astrophysics, and alternative theories of physics are my specialties.

##### Experience

I was a physics professor at the University of Texas of the Permian Basin, research in nuclear technology and nuclear astrophysics. My travelling science show saw over 20,000 students of all ages. I taught physics, nuclear chemistry, radiation safety, vacuum technology, and answer tons of questions as I tour schools encouraging students to consider careers in science. I moved on to a non-academic job with more research just recently.

Education/Credentials
Ph. D. from Duke University in physics, research in nuclear astrophysics reactions, gamma-ray astronomy technology, and advanced nuclear reactors.