Question

On the "Inductance of a Coil" page:

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/indcur.html#c2

the formula that is depicted includes "A" (the "area of the coil"), without delineating WHAT exact "area" is involved, and, in what 'units'.

Is it the full surface area on the *interior*, or on the *exterior*, or both, or is it the cross-sectional area covered by the core (the air, if air-core), or...?

Answer 1

note \(\Phi = BA\), \(\Phi \) is flux