Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: jaiii on 29/07/2013 13:43:53

Title: Is electrical conductivity of air affected by air temperature?
Post by: jaiii on 29/07/2013 13:43:53

Hi.

Dos anybody know:

Is electrical conductivity of air affected by air temperature?

Title: Re: electrical conductivity
Post by: syhprum on 29/07/2013 21:35:52

At modest temperatures the conductivity of air is virtually zero the only current that can pass  thru it is due to the small number of ions or electrons that enter it from space or radioactive sources.
At about 4000°K the vibration of the air molecule's is sufficient to free the outer electrons and there is a rapid transition to a plasma state when the conductivity becomes very high such as in a carbon arc light.

Title: Re: electrical conductivity
Post by: evan_au on 30/07/2013 10:18:30

The dielectric strength (http://en.wikipedia.org/wiki/Dielectric_strength#Breakdown_field_strength) of air is around 3 Million volts per meter, at room temperature.

Almost no current will flow until the voltage reaches these very high levels, such as in a lightning strike.
However, once the air is ionised, the spark/plasma will continue conducting as long as the current is sustained.