Physics question-does anyone know how to do this with the working

taking the resistivity of platinoid as 3.3 x 10-7 m, find the resistance of 7.0 m of platinoid wire of average diameter 0.14 cm.

Explanation:

The resistance of a wire is given by  the equation

where :

is the resistivity of the material

L is the length of the wire

A is the cross-sectional area  of the wire

Here we have  the following data:

 is the resistivity

L = 7.0 m  is the length of the wire

is the diameter of the wire, so the radius is

So the cross-sectional area is

Substituting, the resistance of the wire is:

an ion is a charged atom or molecule. it is charged because the number of electrons do not equal the number of protons in the atom or molecule. an atom can acquire a positive charge or a negative charge depending on whether the number of electrons in an atom is greater or less then the number of protons in the atom.

i don't know that i agree with that but what's the question ?