# Resistance of air

Why the resistance of air is so high?
Its resistivity is approx. 2x10^16 ohm-meter.Trying to compare that when i placed an electron, one in a copper wire and other in air: the one in air seems to be more 'free' than the one in copper wire. If this is not the case then what are those factors that classify air as insulator?elaborate. Thanks in advance.

There are only very few free electrons in air, in stark contrast to the number of free electrons in the wire.

• ok,can i conclude that resistance takes into account the flow of charge due to charges of medium itself-not by the flow of external charges into the medium. only then the medium with lesser free electron will show more resistance? – alto santa Dec 10 '16 at 18:00
• otherwise what will happen if we 'inject' some external electrons into both, copper and air, which will be more conducting? exclude 'internal' charges of media. – alto santa Dec 10 '16 at 18:02
• If you inject electrons (or positive charges, or both, by turning air into a plasma, say) then its conductivity will indeed increase. In general electrical conductivity depends on availability (number density) of electrical charges and their mobility (resistance towards motion), roughly speaking. – Pirx Dec 10 '16 at 18:04
• so if i place two copper plates quite close, the chances of an (and only this) electron to jump accoss one plate to another is higher in 'ionised' air than normal air. the mobility of 'this' elecron is higher when air is ionised? or the mobility of 'a charge' increases when there are other charges around? @prix : thanks for answer – alto santa Dec 10 '16 at 18:25