Answer:
Step-by-step explanation:
If you are using a wire made out of (say) iron the formula would be
R = k * L / (pi * r^2)
pi r^2 represents the cross sectional area.
L is the length of the wire.
k is the resistance constant for that material.
So, resistance is measured as
k which depends on the material. It is different for all materials. Copper Silver and Gold for example, all have different k values.
L is the length of the material
pi * r^2 is the area of a thin slice of this material.