What electron current is driven through a 2.3-mm-diameter iron wire by a 0.063 v/m electric field?

We can find the current flowing through the wire using Ohm's law:

where I is the current,  is the potential difference applied to the wire, and R is the resistance of the wire.

We can now rewrite both  and R. In fact, we know that the potential difference applied to the wire is equal to the product between the intensity of the electric field E applied and the length L of the wire:

Instead, the resistance R is related to the properties of the wire, through the relationship

where  is the resistivity of the material (iron) and A is the cross-sectional area of the wire.

Substituting both formulas into the first one, we get

The section of the wire is 

And by using  and  (iron resistivity), we find