A10-m-long wire with a diameter of 0.80 mm has a resistance of 1.1ω. of what material is the wire made?

The radius of the wire is 

and so the cross-sectional area of the wire is


The relationship between the resistance of the wire R, its length L, its cross-sectional area A and the resistivity of the material  is

So by using the data of the problem we find the resistivity of the material:


And by looking at the table of the resistivities for different materials, we find that this value corresponds to tungsten, so the wire is made of tungsten.

It's because 3 if it was 10 it wouldn't look right do it goes up to 4d