Question

If the radius of cooper wire is double what will be effect on specific restistivity

Answer 1

The resistivity of the wire will be the same

Answer 2

we know,
 $R ={\rho}\frac{L}{A}$
where ,
    R = resistance of wire
    ρ = specific resistance
    L = length of wire 
    A = cross section area 


here, we know specific resitance is a proportionality constant. and it is metallic property. it doesn't  depend upon dimensions of metals.so, we can say that if  radius of wire is doubled then specific resistance won't change